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Boukhzar L, Hamieh A, Cartier D, Tanguy Y, Alsharif I, Castex M, Arabo A, Hajji SE, Bonnet JJ, Errami M, Falluel-Morel A, Chagraoui A, Lihrmann I, Anouar Y. Selenoprotein T Exerts an Essential Oxidoreductase Activity That Protects Dopaminergic Neurons in Mouse Models of Parkinson's Disease. Antioxid Redox Signal 2016; 24:557-74. [PMID: 26866473 PMCID: PMC4840926 DOI: 10.1089/ars.2015.6478] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 02/05/2016] [Accepted: 02/06/2016] [Indexed: 12/22/2022]
Abstract
AIMS Oxidative stress is central to the pathogenesis of Parkinson's disease (PD), but the mechanisms involved in the control of this stress in dopaminergic cells are not fully understood. There is increasing evidence that selenoproteins play a central role in the control of redox homeostasis and cell defense, but the precise contribution of members of this family of proteins during the course of neurodegenerative diseases is still elusive. RESULTS We demonstrated first that selenoprotein T (SelT) whose gene disruption is lethal during embryogenesis, exerts a potent oxidoreductase activity. In the SH-SY5Y cell model of dopaminergic neurons, both silencing and overexpression of SelT affected oxidative stress and cell survival. Treatment with PD-inducing neurotoxins such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or rotenone triggered SelT expression in the nigrostriatal pathway of wild-type mice, but provoked rapid and severe parkinsonian-like motor defects in conditional brain SelT-deficient mice. This motor impairment was associated with marked oxidative stress and neurodegeneration and decreased tyrosine hydroxylase activity and dopamine levels in the nigrostriatal system. Finally, in PD patients, we report that SelT is tremendously increased in the caudate putamen tissue. INNOVATION These results reveal the activity of a novel selenoprotein enzyme that protects dopaminergic neurons against oxidative stress and prevents early and severe movement impairment in animal models of PD. CONCLUSIONS Our findings indicate that selenoproteins such as SelT play a crucial role in the protection of dopaminergic neurons against oxidative stress and cell death, providing insight into the molecular underpinnings of this stress in PD.
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Affiliation(s)
- Loubna Boukhzar
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Abdallah Hamieh
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Dorthe Cartier
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Yannick Tanguy
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Ifat Alsharif
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Matthieu Castex
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Arnaud Arabo
- Faculty of Sciences, University of Rouen, Mont-Saint-Aignan, France
| | - Sana El Hajji
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Jean-Jacques Bonnet
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Mohammed Errami
- Department of Biology, Faculty of Sciences, Abdelmalek Essaadi University, Tetouan, Morocco
| | - Anthony Falluel-Morel
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Abdeslam Chagraoui
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Isabelle Lihrmann
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
| | - Youssef Anouar
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Mont-Saint-Aignan, France
- Com UE, Normandy University of Rouen, France
- Institute for Research and Innovation in Biomedicine, University of Rouen, Mont-Saint-Aignan, Rouen, France
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Castex MT, Arabo A, Bénard M, Roy V, Le Joncour V, Prévost G, Bonnet JJ, Anouar Y, Falluel-Morel A. Selenoprotein T Deficiency Leads to Neurodevelopmental Abnormalities and Hyperactive Behavior in Mice. Mol Neurobiol 2015; 53:5818-5832. [DOI: 10.1007/s12035-015-9505-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/19/2015] [Indexed: 01/27/2023]
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Le Maître E, Dourmap N, Vilpoux C, Leborgne R, Janin F, Bonnet JJ, Costentin J, Leroux-Nicollet I. Acute and subchronic treatments with selective serotonin reuptake inhibitors increase Nociceptin/Orphanin FQ (NOP) receptor density in the rat dorsal raphe nucleus; interactions between nociceptin/NOP system and serotonin. Brain Res 2013; 1520:51-60. [PMID: 23669068 DOI: 10.1016/j.brainres.2013.05.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 12/14/2022]
Abstract
Nociceptin/Orphanin FQ is the endogenous ligand of NOP receptor, formerly referred to as the Opioid Receptor-Like 1 receptor. We have previously shown that NOP receptors were located on serotonergic neurons in the rat dorsal raphe nucleus, suggesting possible direct interactions between nociceptin and serotonin in this region, which is a target for antidepressant action. In the present study, we investigated further the link between Selective Serotonin Reuptake Inhibitor (SSRI) antidepressant treatments and the nociceptin/NOP receptor system. Intraperitoneal administration of the SSRI citalopram induced an increase in NOP-receptor density, measured by autoradiographic [(3)H] nociceptin binding, in the rat dorsal raphe nucleus, from the first to the 21st day of treatment. This effect was also observed with other SSRIs (sertraline, fluoxetine), but not with two tricyclic antidepressants (imipramine, clomipramine) and was abolished by pre-treatment with para-chlorophenylalanine, an inhibitor of serotonin synthesis. Using microdialysis experiments, we demonstrated that NOP-receptor activation by infusion of nociceptin 10(-6) M or 10(-5) M increased the level of extracellular serotonin in the dorsal raphe nucleus. This effect was abolished by co-infusion of the NOP-receptor antagonist UFP 101. These results confirm the existence of reciprocal interactions between serotonin and nociceptin/NOP transmissions in the dorsal raphe nucleus.
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Affiliation(s)
- Erwan Le Maître
- Unité de Neuropsychopharmacologie de la Dépression, EA 4359, IRIB, Faculté de Médecine-Pharmacie, 22 Bd. Gambetta, 76183 Rouen Cedex 1, France
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Cravezic A, Fichna J, Gach K, Wyrebska A, Perlikowska R, Costentin J, Bonnet JJ, Janecka A, do Rego JC. Effect of potent endomorphin degradation blockers on analgesic and antidepressant-like responses in mice. Neuropharmacology 2011; 61:1229-38. [DOI: 10.1016/j.neuropharm.2011.07.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/27/2011] [Accepted: 07/12/2011] [Indexed: 11/16/2022]
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Gembus V, Bonnet JJ, Janin F, Bohn P, Levacher V, Brière JF. Synthesis of pyrazolines by a site isolated resin-bound reagents methodology. Org Biomol Chem 2010; 8:3287-93. [DOI: 10.1039/c004704j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nepveu F, Bonnet JJ, Laurent JP, Massol M. SPECTROSCOPIC AND X-RAY STRUCTURAL STUDY OF THE COPPER(II) COMPLEX WITH SCHIFF BASE BETWEEN PYRIDOXAL AND BENZYLAMINE. J COORD CHEM 2007. [DOI: 10.1080/00958978108079068] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Uptake blockers and substrates are likely to recognise a common binding domain on the dopamine neuronal transporter (DAT). Among cations that form ionic gradients at the level of the cellular plasma membrane, Na+ is the only one that can stimulate their binding. The binding stimulation appears over Na+ concentrations ranging from 0 to 10-60 mM; at higher Na+ concentrations, binding reaches a plateau or decreases, according to the uptake blocker that is studied. The majority of the other cations, including K+, Ca2+, Mg2+ and Tris+, inhibit the binding of uptake blockers. Several metals impair binding to the DAT and/or the dopamine transport, but, under specific conditions, some of them, and chiefly Zn2+, stimulate binding. The complex relationships between cations, uptake blockers and the DAT suggest that cations recognise at least three different sites: the first one, site 1, is for cation-induced binding inhibition; the second one, site 2, is for Na+-induced binding stimulation; and the third one, site 3, is for Zn2+-induced binding stimulation. Modelling of the interactions between Na+, K+ and radioligands allows a better understanding of the effects of cations at sites 1 and 2, and of uptake blockers at site 1. Some anions also facilitate the binding of uptake blockers to the DAT, as far as they are associated with Na+. The dependence of the binding of dopamine on ions could be involved in its preferential inward transport and used by uptake blockers for their own binding to the DAT.
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Affiliation(s)
- Jean-Jacques Bonnet
- UMR CNRS 6036, IFRMP 23, Laboratoire de Neuropsychopharmacologie expérimentale, 22 Boulevard Gambetta, 76000 Rouen, France.
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Legros H, Dingeval MG, Janin F, Costentin J, Bonnet JJ. Toxicity of a Treatment Associating Dopamine and Disulfiram for Catecholaminergic Neuroblastoma SH-SY5Y Cells: Relationships with 3,4-Dihydroxyphenylacetaldehyde Formation. Neurotoxicology 2004; 25:365-75. [PMID: 15019299 DOI: 10.1016/s0161-813x(03)00148-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2003] [Accepted: 07/17/2003] [Indexed: 11/30/2022]
Abstract
3,4-Dihydroxyphenylacetaldehyde (DOPAL) is formed by the oxidative deamination of dopamine (DA) catalyzed by monoamine oxidases (MAO); then, the aldehyde is oxidized to 3,4-dihydroxyphenylacetic acid (DOPAC) by aldehyde dehydrogenases (ALDH) or reduced to 3,4-dihydroxyphenylethanol (DOPET) by aldose/aldehyde reductases. The present work aimed at evaluating the in vitro toxicity of DOPAL on catecholaminergic neuroblastoma SH-SY5Y cells which accumulate DA. DOPAL synthesis was stimulated by incubating cells with DA and blocking DOPAL oxidation by disulfiram, an irreversible inhibitor of ALDH. As evidenced by MTT reduction assays, DA and disulfiram treatments produced cell losses which increased with time. 10(-2)M DA reduced by 40% cell viability after a 1h treatment, when its TC(50) (concentration reducing viability by 50%) value was 7.3 x 10(-5) M after a 24 h treatment. For the same treatment periods, TC(50) values for disulfiram were 8 x 10(-5) and 8.7 x 10 (-7) M, respectively. MTT reduction assay performed after a 24h treatment followed by a 24h incubation in a drug-free medium evidenced that the toxicity of 10(-4)M DA or 10(-6)M disulfiram was potentiated by the second drug. HPLC measurements showed that DOPAL was produced at the early stages of the treatment by DA and disulfiram. This was evidenced by the significant increase in the ((DOPAL + DOPET)/DOPAC ratio observed after a combined 3h treatment by 10(-4)M DA and 10(-6)M disulfiram. Total contents in DA and DOPAL were greatly reduced at the end of a 15 h treatment, and disulfiram did not significantly enhanced the (DOPAL + DOPET)/DOPAC ratio. For both treatment durations, DOPAL and DOPET were detectable only in the extracellular medium. So, these results suggest that an early production of DOPAL could produce delayed toxic effects on SH-SY5Y cells. Production of DOPET and release of DOPAL could be important means for reducing DOPAL concentrations in dopaminergic neurons.
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Affiliation(s)
- Hélène Legros
- Unité de Neuropsychopharmacologie Expérimentale, UMR 6036 CNRS, IFRMP No 23, 22 Boulevard Gambetta, 76183 Rouen Cedex, France
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Legros H, Janin F, Dourmap N, Bonnet JJ, Costentin J. Semi-chronic increase in striatal level of 3,4-dihydroxyphenylacetaldehyde does not result in alteration of nigrostriatal dopaminergic neurones. J Neurosci Res 2004; 75:429-35. [PMID: 14743456 DOI: 10.1002/jnr.10880] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This work was carried out to evaluate the potential in vivo toxicity of 3,4-dihydroxyphenylacetaldehyde (DOPAL), an aldehyde formed from dopamine by monoamine oxidase (MAO) that is oxidised mainly to 3,4-dihydroxyphenylacetic acid (DOPAC) by brain aldehyde dehydrogenases (ALDH). In this study, male Sprague-Dawley rats were treated with levodopa (L-dopa)-benserazide, which increases DOPAL production by MAO, and disulfiram, an irreversible inhibitor of ALDH, which reduces the formation of DOPAC from DOPAL. An acute systemic intraperitoneal (i.p.) injection of 100 mg/kg disulfiram and L-dopa-benserazide (100 mg/kg + 25 mg/kg, 24 hr later) significantly increased DOPAL striatal level. A 30-day treatment with disulfiram (100 mg/kg i.p., once every 2 days) and L-dopa-benserazide (100 mg/kg + 25 mg/kg, two times/day) did not affect either indexes used to assess integrity of the nigrostriatal dopaminergic neurones (i.e., the striatal content in dopamine and binding to the vesicular monoamine transporter on striatal membranes). These results do not evidence any deleterious effect of DOPAL and argue against toxicity of L-dopa therapy.
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Affiliation(s)
- Hélène Legros
- Unité de Neuropsychopharmacologie Expérimentale, UMR 6036 CNRS, IFRMP N 23, Rouen, France
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Maisonnat A, Bonnet JJ, Poilblanc R. Reaction of tetracyanoethylene with the thiolato-bridged d8 diiridium complexes [Ir(.mu.-S-tert-Bu)(CO)(PR3)]2, R = Me, Ph and OMe. Crystal structure of the complex [Ir(.mu.-S-tert-Bu)(CO)(P(OMe)3)]2[C(CN)2]2. Inorg Chem 2002. [DOI: 10.1021/ic50212a067] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Syringas M, Janin F, Giros B, Costentin J, Bonnet JJ. Involvement of the NH2 terminal domain of catecholamine transporters in the Na(2+) and Cl(-)-dependence of a [3H]-dopamine uptake. Br J Pharmacol 2001; 133:387-94. [PMID: 11375255 PMCID: PMC1572801 DOI: 10.1038/sj.bjp.0704097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The ionic dependence of the [3H]-dopamine uptake was studied in transfected cells expressing the human neuronal transporter for dopamine (hDAT) or noradrenaline (hNET), and chimeric transporters resulting from the symmetrical exchange of the region from the NH2 terminal through the first two transmembrane domains (cassette I). Chimera A is formed by hDAT comprising cassette I from hNET, whereas chimera B corresponds to the reverse construct. The appearance or the intensity of a Cl(-)-independent component of transport was linked to the presence of the COOH terminal part of hNET in both monoclonal and polyclonal Ltk(-) cells (Cl(-) substituted by isethionate and NO3(-), respectively), and in transiently transfected COS-7 cells. Cassette I was also involved in the Cl(-)-dependence because the transport activity of polyclonal Ltk(-) cells expressing A was partly Cl(-)-independent and because Ltk(-) cells expressing transporters containing cassette I of hDAT displayed higher K(mCl)- values than cells expressing the reverse constructs. In monoclonal Ltk(-) cell lines, K(mNa)+ values and biphasic vs monophasic dependence upon Na(+) concentrations differentiate transporters containing cassette I of hNET from those containing cassette I of hDAT. In COS-7 cells, the exchange of cassette I produced a significant change in Hill number values. In Na(+)-dependence studies, exchange of the COOH terminal part significantly modified Hill number values in both Ltk(-) and COS-7 cells. Hill number values close to two were found for hNET and hDAT when sucrose was used as substitute for NaCl. The NH2 terminal part of the transporters bears some of the differences in the Na(+) and Cl(-)-dependence of the uptake that are observed between hDAT and hNET. Present results also support a role of the COOH terminal part in the ionic dependence.
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Affiliation(s)
- Maria Syringas
- UMR C.N.R.S. 6036, IFRMP 23, U.F.R. de Médecine & Pharmacie, 22 Boulevard Gambetta, 76000 Rouen, France
| | - François Janin
- UMR C.N.R.S. 6036, IFRMP 23, U.F.R. de Médecine & Pharmacie, 22 Boulevard Gambetta, 76000 Rouen, France
| | - Bruno Giros
- INSERM U513, 8 av. du Général Sarrail, 94000 Créteil, France
| | - Jean Costentin
- UMR C.N.R.S. 6036, IFRMP 23, U.F.R. de Médecine & Pharmacie, 22 Boulevard Gambetta, 76000 Rouen, France
| | - Jean-Jacques Bonnet
- UMR C.N.R.S. 6036, IFRMP 23, U.F.R. de Médecine & Pharmacie, 22 Boulevard Gambetta, 76000 Rouen, France
- Author for correspondence:
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Tidjane Corera A, Do-Régo JC, Costentin J, Bonnet JJ. Differential sensitivity to NaCl for inhibitors and substrates that recognize mutually exclusive binding sites on the neuronal transporter of dopamine in rat striatal membranes. Neurosci Res 2001; 39:319-25. [PMID: 11248372 DOI: 10.1016/s0168-0102(00)00230-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Addition of NaCl (90--290 mM) to a 10 mM Na(+) medium did not significantly modify B(max) and K(d) values for [3H]mazindol binding to the dopamine neuronal transporter (DAT) studied on rat striatal membranes at 20 degrees C. Addition of NaCl differentially affected the ability of other uptake inhibitors and substrates to block the [3H]mazindol binding. Ratios of 50% inhibiting concentrations calculated for 290 and 90 mM NaCl allowed to distinguish three groups of agents: substrates which were more potent in the presence of 290 mM NaCl (group 1; ratio < 1) and two groups of uptake inhibitors displaying ratio values either ranging around two (group 2: WIN 35,428, cocaine, methylphenidate, pyrovalerone) or close to unity (group 3: BTCP, mazindol, benztropine, nomifensine). However, agents from these three groups recognize mutually exclusive binding sites since in interaction studies the presence of WIN 35,428 (group 2) or mazindol (group 3) increased the 50% inhibiting concentrations of D-amphetamine (group 1) and WIN 35,428 on the [3H]mazindol binding to theoretical values expected for a competition of all of these compounds for the same binding domain on the DAT.
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Affiliation(s)
- A Tidjane Corera
- UMR C.N.R.S. 6036, IFRMP 23, U.F.R. de Médecine et Pharmacie, 22 Boulevard Gambetta, 76000, Rouen, France
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Syringas M, Janin F, Mezghanni S, Giros B, Costentin J, Bonnet JJ. Structural domains of chimeric dopamine-noradrenaline human transporters involved in the Na(+)- and Cl(-)-dependence of dopamine transport. Mol Pharmacol 2000; 58:1404-11. [PMID: 11093780 DOI: 10.1124/mol.58.6.1404] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Catecholamine transporters constitute the biological targets for several important drugs, including antidepressants, cocaine, and related compounds. Some information exists about discrete domains of these transporters that are involved in substrate translocation and uptake blockade, but delineation of domains mediating the ionic dependence of the transport remains to be defined. In the present study, human neuronal transporters for dopamine and noradrenaline (hDAT and hNET) and a series of six functional chimeras were transiently expressed in LLC-PK1 cells. Substitution of Cl(-) by isethionate reveals that cassette IV (i.e., the region of the transporter encompassing transmembrane domain 9 through the COOH terminal) plays an important role in the Cl(-)- dependence of the uptake. Substitutions of Na(+) and NaCl by Tris(+) and sucrose, respectively, demonstrate that three different segments scattered across the transporter are involved in the Na(+)- dependence of the transport activity: cassette I (i.e., the region from the amino terminus through the first two transmembrane domains), cassette IV, and junction between transmembrane domains 3 to 5 and 6 to 8. Results of the present work also suggest that the use of Tris(+) as a substitute for Na(+) results in a biased estimate of the Hill number value for hDAT. This study provides useful clues for identifying specific residues involved in the uptake function of the catecholamine transporters.
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Affiliation(s)
- M Syringas
- Unité Propre de Recherche de l'Enseignement Supérieur, Centre National de la Recherche Scientifique 6036, Institut Fédératif de Recherches Multidisciplinaires sur les Peptides 23, Rouen, France
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Corera AT, Costentin J, Bonnet JJ. Binding of uptake blockers to the neuronal dopamine transporter: further investigation about cationic and anionic requirements. Naunyn Schmiedebergs Arch Pharmacol 2000; 362:213-21. [PMID: 10997723 DOI: 10.1007/s002100000280] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Effects of ions on the binding of uptake blockers to the rat dopamine transporter (rDAT) labelled with [3H]WIN 35,428 [2beta-carbomethoxy-3beta-(4-fluorophenyl)-[3H] tropane] and [3H]mazindol were studied at 20 degrees C. [3H]WIN 35,428 binding increased with Na+ concentrations of up to 10-60 mM and decreased at higher concentrations. At pH 7.4, incubation media containing NaCl and/or Na2HPO4/NaH2PO4 were less stimulant than an NaHCO3/NaH2PO4 medium and they shifted maximal binding values to higher ionic concentrations. In an NaHCO3/NaH2PO4-buffered medium, Na+ concentrations >10 mM decreased the binding of 0.2 nM [3H]WIN 35,428, but an increase of the radioligand concentration shifted this decrease to the right. [3H]Mazindol binding was stimulated by Na+ concentrations < or =10 mM and was rather unaffected at higher concentrations. The inhibition of [3H]WIN 35,428 binding produced by 130 mM Na+ was independent of the nature of the anion; in contrast, isothionate and H2PO4-/HCO3 produced a more pronounced inhibition of the [3H]mazindol binding than Cl- and Br-, whereas I- tended to be a stimulant. Ca2+ and Mg2+ more potently inhibited the [3H]WIN 35,428 binding than K+. All these cations recognize a site which is not mutually exclusive with that of the radioligand since they induced the dissociation of the [3H]WIN 35,428-rDAT complex, an effect which was reduced (K+) or modified (Ca2+) when the Na+ concentration was increased. This site is likely to be the Na+ site by which low Na+ concentrations allosterically stimulate the uptake blocker binding. However, the intensity of the cation-induced dissociations was moderate and the main component of the binding inhibition that these cations produced results from the occupancy of a cation site, mutually exclusive with that of the radioligand. Thus, the WIN 35,428 binding inhibition produced by Ca2+, K+ and Na+ was competitive, and Na+ reduced the inhibitory potency of Ca2+ and K+. This reduction was more intense for Ca2+ and Mg2+ than for K+, suggesting that occupancy of the cation site by a divalent cation activated a strong negative allosteric interaction between this site and the Na+ site. Decrease in the Na+ concentration from 10 mM to 5 mM, or replacement of 5 mM HCO3-/H2PO4- by an equimolar concentration of isethionate or Cl- did not modify [3H]WIN 35,428 binding dissociation. Level(s) at which anions stimulate and inhibit the binding of uptake blockers remain uncertain and could be specific for each radioligand.
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Affiliation(s)
- A T Corera
- UPRESA CNRS 6036, UFR de Médecine and Pharmacie, Rouen, France
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Do Régo JC, Syringas M, Leblond B, Costentin J, Bonnet JJ. Recovery of dopamine neuronal transporter but lack of change of its mRNA in substantia nigra after inactivation by a new irreversible inhibitor characterized in vitro and ex vivo in the rat. Br J Pharmacol 1999; 128:51-60. [PMID: 10498834 PMCID: PMC1571617 DOI: 10.1038/sj.bjp.0702784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. In vitro, the ability of DEEP-NCS {1-[2-(diphenylmethoxy)ethyl]-4-[2-(4-isothiocyanatophenyl)ethyl]- piperazine} to inhibit [3H]-dopamine uptake by rat striatal synaptosomes was concentration-dependent and inversely related to the protein concentration. This inhibition was irreversible and resulted from changes in Vmax and KM. DEEP-NCS was less potent on noradrenaline, serotonin and choline transport. 2. One day after intrastriatal injections of DEEP-NCS (100 and 1000 pmol) in 20% dimethylsulphoxide, moderate decreases in the ex vivo dopamine uptake were observed in synaptosomes obtained from striatum injected with DEEP-NCS or solvent, and the contralateral uninjected striatum. 3. In similar conditions, 300 pmol DEEP-NCS in 45% 2 hydroxypropyl-gamma-cyclodextrin - 0.5% dimethylsulphoxide solution sub-totally reduced ex vivo dopamine uptake and mazindol binding, and moderately decreased choline and serotonin transport. These reductions were specific to DEEP-NCS-injected striata. A clomipramine pretreatment (16 mg kg-1 i.p. 1 h before) was performed in following experiments, since it reduced the DEEP-NCS-elicited decrease in serotonin uptake without affecting other indices. 4. One day after intrastriatal injection, DEEP-NCS elicited similar dose-dependent decreases in ex vivo dopamine uptake and mazindol binding (ID50=6.9-8 ng striatum-1). Changes in KM and Vmax for ex vivo dopamine transport produced by DEEP-NCS disappeared according to similar time-courses. 5. The t(1/2) for transporter recovery was 6. 1 days. This value should correspond to its actual turnover rate in vivo, since no change in transporter mRNA level was observed in substantia nigra ipsilateral to 300 pmol DEEP-NCS-injected striatum. 6. The results indicate that DEEP-NCS behaves as a potent, quite selective, irreversible inhibitor of the DAT, in vitro and in vivo. Its use in vivo suggests that the physiological half-life of the rat striatal DAT is close to 6 days.
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Affiliation(s)
- Jean-Claude Do Régo
- UPRESA C.N.R.S. 6036, IFRMP 23, Site Universitaire du Madrillet U.F.R. de Médecine & Pharmacie, 76800, Saint Etienne du Rouvray, France
| | - Maria Syringas
- UPRESA C.N.R.S. 6036, IFRMP 23, Site Universitaire du Madrillet U.F.R. de Médecine & Pharmacie, 76800, Saint Etienne du Rouvray, France
| | - Bertrand Leblond
- Centre Européen de Bioprospective, 24 bis rue J. Boutrolle, 76131 Mont Saint Aignan Cedex, France
| | - Jean Costentin
- UPRESA C.N.R.S. 6036, IFRMP 23, Site Universitaire du Madrillet U.F.R. de Médecine & Pharmacie, 76800, Saint Etienne du Rouvray, France
| | - Jean-Jacques Bonnet
- UPRESA C.N.R.S. 6036, IFRMP 23, Site Universitaire du Madrillet U.F.R. de Médecine & Pharmacie, 76800, Saint Etienne du Rouvray, France
- Author for correspondence:
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Cleren C, Vilpoux C, Dourmap N, Bonnet JJ, Costentin J. Acute interactions between L-DOPA and the neurotoxic effects of 1-methyl-4-phenylpyridinium or 6-hydroxydopamine in mice. Brain Res 1999; 830:314-9. [PMID: 10366688 DOI: 10.1016/s0006-8993(99)01420-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We have compared the effects of an i.p. pretreatment with L-DOPA (200 mg/kg) associated with benserazide (25 mg/kg) on neurotoxic effects of either 6-hydroxydopamine (6-OHDA) (50 microg, 10 microl per mouse) or 1-methyl-4-phenylpyridinium (MPP+) (17.5 microg, 10 microl per mouse). The striatal dopamine (DA) content, the vesicular monoamine transporter (VMAT2) density, as well as the hypothalamic norepinephrine (NE) content were measured 8 days after treatments. The L-DOPA-benserazide pretreatment worsened by 65% the 6-OHDA-induced depletion in striatal DA. On the contrary, it reduced by 42% the MPP+-induced depletion in striatal DA and by 54% the MPP+-induced decrease in VMAT2 density. It was noticed that the L-DOPA-benserazide pretreatment did not modify the marked decrease in hypothalamic NE content induced by 6-OHDA.
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Affiliation(s)
- C Cleren
- Unité de Neuropsychopharmacologie Expérimentale, UPRES-A CNRS 6036, IFRMP N 23, Site universitaire du Madrillet, Avenue de l'Université, 76800, Saint-Etienne du Rouvray, France
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Bliman S, Bonnet JJ, Chauvet G, Dousson S, Hitz D, Jacquot B, Knystautas EJ. Radiative decay of lithium-like ions following charge exchange collisions of 3 keV amu-1C4+ions with H2. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/16/8/007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Politis MF, Jouin H, Bonnefoy M, Bonnet JJ, Chassevent M, Fleury A, Bliman S, Harel C. Relative (n, l) populations following electron capture by low energy N7+, O8+and Ne8+ions from two-electron targets (H2, He). ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/20/10/019] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Baptist R, Bonnet JJ, Chauvet G, Desclaux JP, Dousson S, Hitz D. Polarisation of light emitted after charge transfer from H2to C4+ions. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/17/12/007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Do-Régo JC, Hue H, Costentin J, Bonnet JJ. Evidence for the sequential formation of two complexes between an uptake inhibitor, GBR 12783 [1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-propenyl)piperazine], and the neuronal transporter of dopamine. J Neurochem 1999; 72:396-404. [PMID: 9886093 DOI: 10.1046/j.1471-4159.1999.0720396.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Incubation of a crude synaptosomal fraction from rat striatum with GBR 12783 at 37 degrees C produced an inhibition of the specific uptake of [3H]dopamine that increased with time. The inhibition increased when GBR 12783 was present during preincubation and incubation (IC50 = 1.85+/-0.1 nM) instead of incubation alone (IC50 = 25+/-3.5 nM). Time-course studies of uptake inhibition demonstrated that a first collision transporter-inhibitor complex (TI) was formed immediately after addition of GBR 12783 so that the initial uptake velocity (V0) decreased for increasing concentrations of inhibitor (Ki > or = 20 nM). TI slowly isomerized to a more stable complex TI* (Ki* < or = 5 nM) with a value of t1/2 = 20-270 s. Fits of data to model 2 in which the steady-state uptake (VS) is set to zero were generally preferred, suggesting that formation of TI* could tend to irreversibility, as a consequence of a very low reverse isomerization. As expected, k, V0, and VS tended to steady-state values in an asymptotic manner for high concentrations of GBR 12783. GBR 12783 at 2.5 nM produced a mixed inhibition of the uptake, with an increase in KM and a decrease in Vmax; these effects were improved for 10 nM GBR 12783 and at 20 degrees C. These results are discussed in relation to previous data concerning [3H]GBR 12783 binding. The present work gives the first experimental demonstration that dopamine uptake blockers can act according to a two-step mechanism of inhibition; this is of great interest, because these inhibitors can oppose the effects of cocaine or amphetamine on the transporter according to a reaction that is partly nondependent on the concentration of the abused agent.
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Affiliation(s)
- J C Do-Régo
- UPRESA CNRS 6036, IFRMP 23, UFR de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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Cornille M, Dubau J, Bely-Dubau F, Bliman S, Hitz D, Mayo M, Bonnet JJ, Bonnefoy M, Chassevent M, Fleury A. Spectroscopy of doubly excited Ne VII produced in low-energy charge exchange collisions. ACTA ACUST UNITED AC 1999. [DOI: 10.1088/0022-3700/19/11/002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Affiliation(s)
- A T Corera
- Laboratoire de Neuropsychopharmacologie Expérimentale, UFR de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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Corera AT, Costentin J, Bonnet JJ. Effect of low concentrations of K+ and Cl- on the Na(+)-dependent neuronal uptake of [3H] dopamine. Naunyn Schmiedebergs Arch Pharmacol 1996; 353:610-5. [PMID: 8738293 DOI: 10.1007/bf00167179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The specific uptake of [3H] dopamine (DA) was studied using a crude synaptosomal fraction obtained from rat striatum. In a medium containing a 10 mM NaHCO3/NaH2PO4 buffer and no added K+ ions, addition of NaCl elicited an increase in DA uptake for Na+ concentrations from 10 to 60 mM, and then a decrease of uptake for Na+ concentrations up to 130 mM. These data confirm that rather low NaCl concentrations produce a maximal DA uptake. This biphasic curve of uptake resulted from significant changes in the Vmax of the DA uptake. Except for 10 mM Na+, this curve was not significantly modified when 9 mM NaHCO3/NaH2PO4 were replaced by 9 mM NaCl. This result indicates that the Cl- dependence of the DA uptake is mainly secondary to the Na+ dependence. Addition of KCl up to 3 mM did not modify the ascending part of the NaCl-dependent uptake curve. In contrast, the reduction in uptake produced by high Na+ concentrations was prevented in a concentration-dependent manner by KCl; this effect resulted from a decrease in the Km and an increase in the Vmax for the uptake. Measurements of membrane potential, with the help of the fluorescent probe 3, 3'-diethylthiadicarbocyanine iodide [DiSC2(5)] and purified synaptosomes prepared from rat striatum and cerebral cortex, revealed that addition of 3 mM KCl to a medium containing a high Na+ concentration and no K+ ions produced a marked and stable decrease in the fluorescence level. This decrease which corresponds to an increase in membrane polarization was blocked by 0.1 mM ouabain. These data suggest that low K+ concentrations are likely to prevent the decrease in uptake elicited by high Na+ concentrations by restoration, via a Na+/K+ ATPase-mediated mechanism, of the membrane potential and/or a transmembrane electrochemical Na+ gradient more favourable to DA uptake.
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Affiliation(s)
- A T Corera
- URA 1969 du C.N.R.S., U.F.R. de Médecine & Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Abstract
At 20 degrees C, [3H]GBR 12783, {1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-([1-3H]propenyl)-pip era zine} dissociated from the dopamine neuronal carrier present in rat striatal membranes with a t1/2 value of 27 min. At this temperature, KCI, CaCl2 and MgCl2 increased the binding dissociation, revealing that they recognize a binding site which is not mutually exclusive with that of [3H]GBR 12783. The comparison of the ability of KCl to increase the binding dissociation (by 160% at 30 mM KCl) with its potency as a binding inhibitor (Ki-2.6 +/- 0.3 mM) suggests an involvement of two recognition sites for K+ in binding inhibition, a not mutually exclusive site and another, mutually exclusive, site. Divalent cations mainly inhibited the binding via a mutually exclusive site since 3 mM Ca2+ and 10 mM Mg2+ increased the binding dissociation by 90% at 20 degrees C whereas their Ki values were 0.049 +/- 0.006 and 0.141 +/- 0.035 mM, respectively. Involvement of this mutually exclusive site was also supported by the persistence of the binding inhibition elicited by Ca2+ and Mg2+ at 0 degree C, a temperature at which they reduced the binding dissociation. At 20 degrees C, 100 mM NaCl did not modify [3H]GBR 12783 binding but it antagonized the binding dissociation elicited by inhibitory cations. Ca2+ reduced the off-rate of [3H]GBR 12783 binding at 0 degree C and in the presence of 100 mM Na+. Finally, [3H]GBR 12783-binding dissociation was increased by high 'cytosolic' K+ while 'synaptic' concentrations of Na+, K+, Ca2+, Mg2+ and Cl- were ineffective. A reduction of H2PO4-/HCO3- from 10 to 5 mM and a substitution of 5 mM H2PO4-/HCO3- by 5 mM Cl- increased the binding dissociation, suggesting that an anion-binding site could also regulate the binding.
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Affiliation(s)
- C Héron
- URA 1969, CNRS, UFR de Médecine et Pharmacle, Saint Etienne du Rouvray, France. p4
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Thibaut F, Bonnet JJ, Vaugeois JM, Costentin J. Pharmacological modifications of dopamine transmission do not influence the striatal in vivo binding of [3H]mazindol or [3H]cocaine in mice. Neurosci Lett 1996; 205:145-8. [PMID: 8852579 DOI: 10.1016/0304-3940(96)12399-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have considered the in vivo striatal binding of two ligands of the neuronal dopamine uptake complex: [3H]cocaine and [3H]mazindol. The [3H]cocaine tracer dose labelled the dopamine uptake complex in striatum but not the noradrenaline complex in cerebellum. On the contrary, the [3H]mazindol tracer dose induced a marked labelling of the noradrenaline uptake complex in cerebellum; its prevention by desipramine (5 mg/kg) increased simultaneously the cerebral bioavailability and thereby the striatal labelling of the dopamine transporter. In mice submitted to treatments modifying dopaminergic transmission either to decrease it (gammabutyrolactone, 750 mg/kg, i.p.) or to increase it (L-DOPA, 200 mg/kg, i.p., dexamphetamine, 4 mg/kg, s.c., or their combination), only dexamphetamine pretreatment significantly reduced [3H]cocaine and [3H]mazindol binding. Thus it appears that the level of dopamine transmission would not interfere with the in vivo quantification of striatal dopamine uptake sites assessed with either ligands.
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Affiliation(s)
- F Thibaut
- U.R.A. 1969 CNRS, Institut Fédératif de Recherches Multidisciplinaires sur les Peptides, Saint Etienne du Rouvray, France
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Thibaut F, Vaugeois JM, Bonnet JJ, Costentin J. In vivo striatal binding of the D1 antagonist SCH 23390 is not modified by changes in dopaminergic transmission. Neuropharmacology 1996; 35:267-72. [PMID: 8783200 DOI: 10.1016/0028-3908(95)00187-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The in vivo striatal binding of [3H]SCH 23390, an antagonist of the D1 dopamine receptors, was investigated in mice submitted to pretreatment to either decrease (gammabutyrolactone 750 mg/kg, i.p.) or, increase (3,4-dihydroxyphenylalanine (L-DOPA) 200 mg/kg i.p. plus dexamphetamine 4 mg/kg, s.c.) dopaminergic transmission. Such conditions failed to modify [3H]SCH 23390 binding. However, we observed that dopamine (at concentrations > or = 1 microM), reduced the in vitro binding of [3H]SCH 23390 in membrane fractions. These results suggest that modifications in dopamine neurotransmission do not alter the in vivo quantification of D1 receptors with [3H]SCH 23390, for example, in studies that use positron emission tomography.
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Affiliation(s)
- F Thibaut
- Unité de Neuropsychopharmacologie Expérimentale, Saint Etienne du Rouvray, France
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Naudin B, Bonnet JJ, Costentin J. Acute L-DOPA pretreatment potentiates 6-hydroxydopamine-induced toxic effects on nigro-striatal dopamine neurons in mice. Brain Res 1995; 701:151-7. [PMID: 8925278 DOI: 10.1016/0006-8993(95)00988-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have studied the effect of various agents on the decreases in striatal levels of dopamine (DA) and its metabolites which were observed 14 days after an intracerebroventricular (i.c.v.) administration of 50 micrograms 6-hydroxydopamine (6-OHDA) to mice. A pretreatment of mice with either a tyrosine hydroxylase inhibitor (alpha-methyl-p-tyrosine), a D2 receptor agonist (bromocriptine) or antagonist (haloperidol), or a vesicular uptake inhibitor (tetrabenazine) did not modify the 6-OHDA-induced decreases in DA and metabolites, indicating that DA synthesis, vesicular storage and neuronal firing rates are not mainly involved in the 6-OHDA-induced toxicity on the DA neurons. Conversely, a pretreatment with L-DOPA + benserazide potentiated the 6-OHDA-induced decreases in striatal levels of DA, homovanillic acid and 3-methoxy-tyramine. This effect was not due to an increased 6-OHDA uptake via the neuronal carrier since a pretreatment with L-DOPA + benserazide, performed 1-1.5 h before sacrifice, decreased the apparent affinity of the uptake, an effect which disappeared when considering the total DA concentration present in incubation medium ([3H]DA and cold released DA). In conclusion, potentiation of the 6-OHDA neurotoxicity by L-DOPA rises again the important problem of the safety of the latter drug in therapeutics.
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Affiliation(s)
- B Naudin
- Laboratoire de Neuropsychopharmacologie Expérimentale, Faculté de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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Refahi-Lyamani F, Saadouni S, Costentin J, Bonnet JJ. Interaction of two sulfhydryl reagents with a cation recognition site on the neuronal dopamine carrier evidences small differences between [3H]GBR 12783 and [3H]cocaine binding sites. Naunyn Schmiedebergs Arch Pharmacol 1995; 351:136-45. [PMID: 7770096 DOI: 10.1007/bf00169327] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have compared the effect of treating rat striatal cell membranes with ionic hydrophilic sulfhydryl reagents on the specific bindings of [3H]cocaine and of [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-[1-3H]propenyl)-piperaz ine) to the neuronal transporter of dopamine. Treatment with 1 mmol/l 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) resulted in similar time- and concentration-dependent reductions of the specific binding of both radioligands. None of the uptake blockers tested afforded any protection against 1 mmol/l DTNB. Addition of (sub)millimolar concentrations of CaCl2 or MgCl2, or 250 mmol/l KCl to a treatment medium containing 10 mmol/l Na+ significantly increased the DTNB-induced reduction of the specific binding of both radioligands. Cations were likely to be responsible for this effect since ions in combination with DTNB induced similar reductions in binding when either 1 mmol/l CaCl2 or 50-250 mmol/NaCl were added. Effects of cations on the DTNB-induced inhibition of binding were generally more marked on [3H]GBR 12783 than on [3H]cocaine binding. When added to a medium containing 10 mmol/l Na+ 1 mmol/l DTNB induced a reduction in the Bmax of the specific binding of both radioligands. Addition of 1 mmol/l Ca2+ maintained or increased this Bmax reduction and elicited a decrease in affinity which was significant for [3H]GBR 12783 binding. Treatment of membranes with the sodium salt of p-hydroxymercurybenzenesulfonate (pHMBS) induced time- and concentration-dependent decreases in [3H]GBR 12783 binding which were significantly greater than decreases in [3H]cocaine binding. However, 50 mumol/l pHMBS produced a similar decrease in the Bmax of the specific binding of both radioligands. The pHMBS-induced reduction of [3H]GBR 12783 binding was not reversed by drugs whose action is purely that of uptake inhibition or by substrates of the dopamine carrier. Some of these drugs (100 mumol/l dopamine, 1 mumol/l mazindol or 100 mumol/l cocaine) protected the specific binding of [3H]cocaine against the effects of pHMBS, whereas 1 mmol/l p-tyramine, 10 mumol/l nomifensine and 10 nmol/l GBR 12783 were ineffective. Addition of 120 mmol/l Na+, 1 mmol/l Ca2+ or 10 mmol/l Mg2+ to a treatment medium containing 10 mmol/l Na+ significantly reduced the effects of pHMBS on the specific binding of both radioligands. When striatal cell membranes were treated in a medium containing 130 mmol/l Na+, there was a general decrease in the effects of ions on the reductions of specific binding produced by DTNB or pHMBS.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- F Refahi-Lyamani
- EP 076 du C.N.R.S., U.F.R. de Médecine and Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Abstract
We have studied the ability of various uptake blockers to protect the dopamine neuronal carrier labeled with [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-(propenyl)-piperazine) against N-ethylmaleimide-induced alkylation, using membrane preparations obtained from rat striatum. Pure uptake inhibitors such as mazindol, pyrovalerone, nomifensine and methylphenidate, and substrates (dopamine, d-amphetamine, m-tyramine) protected the [3H]GBR 12783 binding site in a concentration-dependent manner. Preincubation of the membranes with these agents prior to N-ethylmaleimide treatment did not modify the protecting ability of substrates, whereas it significantly improved that of pure uptake inhibitors including cocaine. When the preincubation was omitted, the concentration dependence of the protection observed with pure uptake inhibitors decreased and a maximal 40% protection was observed for 10 microM to 1 mM cocaine concentrations. Effective protecting concentrations of blockers are correlated with their Ki determined in standard binding studies. These results reveal that all pure uptake inhibitors bind slowly to the dopamine neuronal carrier whereas substrates interact with it rapidly.
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Affiliation(s)
- C Héron
- EP 076 du C.N.R.S., U.F.R. de Médecine & Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Billaud G, Menard JF, Marcellin N, Kamenka JM, Costentin J, Bonnet JJ. Thermodynamics of the binding of BTCP (GK 13) and related derivatives on the dopamine neuronal carrier. Eur J Pharmacol 1994; 268:357-63. [PMID: 7805759 DOI: 10.1016/0922-4106(94)90060-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have studied the thermodynamic properties of the binding of a coherent series of uptake inhibitors derived from BTCP (GK 13 = N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine) to the dopamine neuronal carrier labelled with [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-propenyl)-piperazine). GK 13 (30 nM) and its 2-naphthyl derivative GK 189 (15 nM) competitively inhibited the specific binding of [3H]GBR 12783 to sites present in rat striatal membranes. Hill numbers calculated for the inhibition of the specific binding of [3H]GBR 12783 by BTCP derivatives were close to 1 (range 0.79-1.18). Increasing the temperature from 0 degrees to 30 degrees C induced a decrease in the affinity of [3H]GBR 12783 and GK derivatives which was generally less pronounced than that obtained when temperature was raised from 30 degrees C to 37 degrees C. Increasing the incubation temperature led to a decrease in both enthalpy (delta H degrees) and entropy (delta S degrees). We observed at 37 degrees C a large negative enthalpy change (range -48, -79 kJ/mol) and a negative, binding unfavorable, change in entropy. This indicates that the GK derivatives binding is enthalpy-driven. Furthermore, data obtained in the present study show that changes in thermodynamic parameters are not a function of the inhibitor's affinity for the dopamine neuronal carrier and this suggests that bonds involved in the inhibitor-carrier interaction are more likely related to the carrier configuration than to the chemical structure of the inhibitor.
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Affiliation(s)
- G Billaud
- EP 076 du C.N.R.S., U.F.R. de Médecine & Pharmacie de Rouen BP 97, Saint Etienne du Rouvray, France
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Saadouni S, Refahi-Lyamani F, Costentin J, Bonnet JJ. Cocaine and GBR 12783 recognize nonidentical, overlapping binding domains on the dopamine neuronal carrier. Eur J Pharmacol 1994; 268:187-97. [PMID: 7957640 DOI: 10.1016/0922-4106(94)90188-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In incubation medium containing Na+ as the only cation, the specific binding of [3H]cocaine to a membrane preparation obtained from rat striatum reached a maximal level for 10 mM Na+, whereas higher concentrations decreased its affinity. The specific binding of [3H]cocaine was inhibited monophasically by GBR 12783, mazindol, nomifensine and substrates of the transporter; in saturation experiments, GBR 12783 competitively blocked the [3H]cocaine specific binding and vice versa. Treatment of the striatal membranes with N-ethylmaleimide resulted in a concentration-dependent reduction of the specific binding of [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-[1-3H]propenyl)-piperaz ine) which was significantly more marked than that of the specific binding of [3H]cocaine, the nonspecific binding of [3H]cocaine being measured with either cocaine or dopamine. Addition of substrates or pure uptake inhibitors to the treatment medium afforded protection against the N-ethylmaleimide-induced reduction in both bindings. In particular, cocaine offered protection for [3H]GBR 12783 binding and vice versa. All results are consistent with a model in which pure uptake blockers and substrates recognize nonidentical but overlapping binding domains on the neuronal carrier of dopamine.
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Affiliation(s)
- S Saadouni
- EP 076 du C.N.R.S., U.F.R. de Médecine & Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Chanut E, Bonnet JJ, Trouvin JH, Plat M, Costentin J, Jacquot C. 6-Fluoro-serotonin as a substrate for the neuronal serotonin transporter. J Neural Transm (Vienna) 1994; 96:105-12. [PMID: 7857594 DOI: 10.1007/bf01277932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
6-Fluoro-serotonin (6F-5-HT) was previously identified in the rat brain after peripheral administration of 6-fluoro-DL-tryptophan, a serotonin (5-HT) synthesis inhibitor. These present studies, performed with rat brain synaptosomes show that: i-neuronal 6F-5-HT uptake partly involved the 5-HT transporter since it was inhibited by clomipramine, a 5-HT uptake inhibitor, ii-6F-5-HT blocked the synaptosomal uptake of 3H-5-HT, with an IC50 value of 98 +/- 13 nM, and iii- 6F-5-HT induced 3H-5-HT release from preloaded synaptosomes, with an EC50 value of 95 +/- 6 nM; this release was decreased in the presence of clomipramine, suggesting the involvement of the 5-HT transporter. This release was also reduced when using synaptosomes from reserpinized rats, suggesting that the vesicular pool also participates to the 3H-5-HT release induced by 6F-5-HT. So, 6F-5-HT behaved as a substrate for the 5-HT neuronal transporter.
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Affiliation(s)
- E Chanut
- Lab. Pharmacologie, Faculté de Pharmacie, Châtenay-Malabry, France
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Bonnet JJ, Benmansour S, Amejdki-Chab N, Costentin J. Effect of CH3HgCl and several transition metals on the dopamine neuronal carrier; peculiar behaviour of Zn2+. Eur J Pharmacol 1994; 266:87-97. [PMID: 8137886 DOI: 10.1016/0922-4106(94)90213-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
CH3Hg+ and metal ions inhibited the specific binding of (1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-[1-3H]propenyl) piperazine) ([3H]GBR 12783) to the dopamine neuronal carrier present in membranes from rat striatum with a general rank order of potency CH3Hg+ > Cu2+ > Cd2+ > Zn2+ > Ni2+ = Mn2+ = Co2+, suggesting that -SH groups are chiefly involved in this inhibition. Five millimolar dithiothreitol reversed the rather stable block of the specific binding produced by Cd2+ or Zn2+. An increase in the concentration of Na+, or addition of either K+ or Ca2+ reduced the inhibitory effects of metal cations, except Cu2+. Zn2+ (3 microM) reduced the inhibitory potency of Cd2+ on the binding but was ineffective against CH3Hg+ and Cu2+. Zn2+ at 0.3 to 10 microM significantly enhanced the specific binding of [3H]GBR 12783 and [3H]cocaine by 42 to 146%. Zn2+ (3 microM) increased the affinity of all pure uptake inhibitors tested and of the majority of the substrates for the [3H]GBR 12783 binding site. Dissociation experiments revealed that Zn2+ both inhibited and enhanced the [3H]GBR 12783 binding by recognizing amino acids located close to or in the radioligand binding site. Micromolar concentrations of Zn2+ noncompetitively blocked the [3H]dopamine uptake but they did not modify the block of the transport provoked by pure uptake inhibitors. These findings suggest that Na+, K+, Ca2+ and metal ions could recognize some -SH groups located in the [3H]GBR 12783 binding site; low concentrations of Zn2+ could allow a protection of these -SH groups.
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Affiliation(s)
- J J Bonnet
- ERS 019 du CNRS, UFR de Médecine & Pharmacie de Rouen, Saint Etienne du Rouvray, France
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34
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Abstract
We have compared the properties of the binding to the neuronal dopamine carrier located either in polarized membranes of synaptosomes or in non polarized, classical membranes. Non-polarized membranes were prepared by sonication of the partially purified synaptosomal fraction obtained from rat striatum which was used as the source of polarized membranes. Binding experiments were carried out at 37 degrees C in Krebs Ringer related media. [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]4-(3-phenyl-2-[1- 3H]propenyl)piperazine) specifically bound with a nanomolar affinity to a homogeneous population of site (maximal binding site concentration: 8-10 pmol/mg protein). Pure uptake inhibitors, but not substrates, competed for the [3H]GBR 12783 binding site located in polarized membranes of synaptosomes at concentrations effective against dopamine neuronal transport. Except for [3H]GBR 12783, the replacement of Cl- by isethionate- did not result in significant change in the ability of pure uptake inhibitors to compete for the specific binding site. A reduction in the Na+ concentration from 135 to 10 mM induced a significant decrease in the inhibitory potency of GBR 12783, mazindol, nomifensine and methylphenidate. This decrease was likely to result from the presence of K+, Mg2+ and Ca2+, whose inhibitory effects were modified and/or increased by decreasing the Na+ concentration. These data indicate that the membrane polarity is not clearly involved in the binding of pure uptake inhibitors to the dopamine neuronal carrier; furthermore they underline the critical role of Na+ and K+ transmembrane gradients in both the recognition of the carrier by dopamine and its inward transport.
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Affiliation(s)
- G Billaud
- ERS 19 du C.N.R.S., U.F.R. de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Vaugeois JM, Bonnet JJ, Duterte-Boucher D, Costentin J. In vivo occupancy of the striatal dopamine uptake complex by various inhibitors does not predict their effects on locomotion. Eur J Pharmacol 1993; 230:195-201. [PMID: 8422901 DOI: 10.1016/0014-2999(93)90802-o] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We compared the ability of various dopamine (DA) uptake inhibitors to displace the in vivo striatal [3H]GBR 12783 (1-[2(diphenylmethoxy) ethyl)-4-(3-phenyl-1[3H]-2-propenyl)-piperazine) binding with their stimulant effect on locomotor activity on mice. GBR 12783 (8 mg/kg), GBR 13069 (10 mg/kg), cocaine (20 mg/kg), mazindol (3 mg/kg) or pyrovalerone (2 mg/kg) stimulated locomotion as long as they occupied the DA uptake complex. In contrast, nomifensine (3 mg/kg) did not stimulate locomotion although it competed with [3H]GBR 12783 for the occupancy of the DA uptake complex at a significant level (> 50%). Administered at their ED50 doses, GBR 12783, BTCP (N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine, GBR 13069, amineptine and dexamphetamine significantly increased locomotor activity whereas the other inhibitors tested did not. The locomotor response elicited by GBR 12783 (10 mg/kg) was not decreased by desipramine (20 mg/kg) nor by oxaprotiline (10 mg/kg). The increase in locomotion elicited by GBR 12783 was positively correlated with the basal locomotor activity of the mice. The stimulant effect of GBR 12783 was potentiated by SKF 525A and by budipine. Additional pharmacological properties might conceal the relationship between the effects of some DA uptake inhibitors on locomotion, and on in vivo occupancy of DA uptake sites.
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Affiliation(s)
- J M Vaugeois
- Unité de Neuropsychopharmacologie Expérimentale, URA 1170 CNRS, Faculté de Médicine and Pharmacie de Rouen, Saint-Etienne du Rouvray, France
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Amejdki-Chab N, Benmansour S, Costentin J, Bonnet JJ. Effects of several cations on the neuronal uptake of dopamine and the specific binding of [3H]GBR 12783: attempts to characterize the Na+ dependence of the neuronal transport of dopamine. J Neurochem 1992; 59:1795-804. [PMID: 1402923 DOI: 10.1111/j.1471-4159.1992.tb11012.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have studied the effects of several cations on (1) the neuronal uptake of [3H]dopamine ([3H]DA) and (2) the specific binding of 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-[1-3H]propenyl)piperazi ne ([3H]GBR 12783) to a site associated with the neuronal carrier of DA, in preparations obtained from rat striatum. When studied under the same experimental conditions, both the uptake of [3H]DA and the binding of [3H]GBR 12783 were similarly impaired by the gradual replacement of NaCl by sucrose. In both processes, no convenient substitute for Na+ was found. Furthermore, potential substitutes of Na+ acted as inhibitors of the uptake with a rank order of potency as follows: K+ = Li+ > or = Cs+ > or = Rb+ > choline+ > Tris+ > sucrose, which was somewhat different from that observed in binding studies, i.e., Cs+ > Rb+ > choline+ > or = K+ > Li+ > Tris+ > sucrose. In the presence of either 36 mM or 136 mM Na+, [3H]DA uptake was optimal with 2 mM Mg2+, 1 mM K+, or 1 mM Ca2+. In contrast, higher concentrations of divalent cations competitively blocked the uptake process. K+ concentrations > 50 mM impaired the specific binding, whereas in the millimolar range of concentrations, K+ noncompetitively inhibited the uptake. Decreasing the Na+ concentration increased the inhibitory effect of K+, Ca2+, and Mg2+ on the specific uptake. An increase in NaCl concentration from 0 to 120 mM elicited a significant decline in the affinity of some substrates for the [3H]GBR 12783 binding site. An uptake study performed using optimal experimental conditions defined in the present study revealed that decreasing Na+ concentration reduces the affinity of DA for the neuronal transport. We propose a hypothetical model for the neuronal transport of DA in which both Na+ and K+ membrane gradients are involved.
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Affiliation(s)
- N Amejdki-Chab
- URA 1170 du CNRS, UFR de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France
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37
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Abstract
Various characteristics of the in vivo striatal binding of [3H]GBR 12783 (1-[2-(diphenylmethoxy)-ethyl]-4-(3-phenyl-1[3H]-2-propenyl)pipera zine), a specific ligand of the neuronal dopamine uptake complex, were determined in mice. Increasing doses of the ligand revealed the saturability of the binding at a single site with half-maximal saturation at a dose of approximately 7 mumol/kg and an apparent maximal number of binding sites (Bmax) of 12.8 pmol/mg protein in striatum. Specific binding was prevented by various dopamine uptake blockers, pyrovalerone, GBR 13069, GBR 12783, N-[1-2-benzo(b)thiophenyl)cyclohexyl] piperidine, cocaine, methylphenidate and was inhibited in a stereoselective manner by the enantiomers of nomifensine. Other drugs which are not dopamine uptake blockers either did not modify [3H]GBR 12783 binding (the diphenylbutylpiperazine derivative flupenthixol) or increased it (the diphenylpiperazine derivative flunarizine or the chemically unrelated compounds fenfluramine and SKF 525A). A close correlation was found between occupancy of the striatal [3H]GBR 12783 binding site and the stimulant locomotor effect of the drug. A similar specific striatal binding of [3H]GBR 12783 was evidenced in both NMRI and CD1 strains. It was concluded that [3H]GBR 12783 administered in vivo provides a measure of the density of dopamine uptake sites in mouse striatum.
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Affiliation(s)
- J M Vaugeois
- Unité de Neuropsychopharmacologie Expérimentale, U.R.A. 1170 CNRS, Faculté de Médecine et Pharmacie de Rouen, Saint-Etienne du Rouvray, France
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Lancelot JC, Robba M, Bonnet JJ, Vaugeois JM, Costentin J. Synthesis and preliminary study of the activity of thiophene analogues of pyrovalerone on the neuronal uptake of the monoamines. Eur J Med Chem 1992. [DOI: 10.1016/0223-5234(92)90015-s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Amejdki-Chab N, Costentin J, Bonnet JJ. Kinetic analysis of the chloride dependence of the neuronal uptake of dopamine and effect of anions on the ability of substrates to compete with the binding of the dopamine uptake inhibitor GBR 12783. J Neurochem 1992; 58:793-800. [PMID: 1737991 DOI: 10.1111/j.1471-4159.1992.tb09327.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The specific binding of [3H]1-[2-(diphenyl-methoxy)ethyl]-4-(3-phenyl-2-propenyl)piperazine ([3H]GBR 12783) to the dopamine (DA) neuronal carrier present in membranes prepared from rat striatum was not affected when Cl- was replaced by either Br- or NO3-. In media containing Cl-, Br-, or NO3-, d-amphetamine and DA competed with the radioligand in a monophasic manner with Hill coefficients of close to 1 (0.94-1.12). Replacement of Cl- by Br- impaired the ability of some substrates (d-amphetamine, DA, p-hydroxyamphetamine, and m-tyramine) to compete with [3H]GBR 12783. The potency of Br- to decrease the affinity of substrates for the specific binding site was significantly correlated (t = 7.07, p less than 0.001) with their affinity for this binding site. These results suggest that the various substrates tested could bind to recognition sites in which Cl- is differently involved; as a consequence, substrates could bind to the neuronal carrier by means of partly different links. In experiments dealing with the specific uptake of [3H]DA, F-, NO3-, isethionate-, or acetate- was unable to substitute for Cl-, whereas Br- was quite a total substitute. Replacement of Cl- by equimolar concentrations of either NO3- or isethionate- resulted in inhibition curves of DA specific uptake with Hill coefficients of close to 1 (0.77 and 1.04 respectively); this indicates that both NO3- and isethionate- are devoid of inhibitory effects on neuronal uptake and are quite ineffective substitutes for Cl-.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N Amejdki-Chab
- U.A. 1170 du CNRS, U.F.R. de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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40
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Bonnet JJ, Benmansour S, Costentin J, Parker EM, Cubeddu LX. Thermodynamic analyses of the binding of substrates and uptake inhibitors on the neuronal carrier of dopamine labeled with [3H]GBR 12783 or [3H]mazindol. J Pharmacol Exp Ther 1990; 253:1206-14. [PMID: 2141637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have investigated the thermodynamic properties of the binding of substrates and uptake blockers to the specific sites labeled with a tritiated dopamine uptake inhibitor (i.e., 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-propenyl)piperazine ([3H] GBR 12783) or [3H]mazindol) using striatal membrane preparations. Raising the incubation temperature from 0 degrees C to 25 degrees C or 37 degrees C resulted in an increase in the dissociation constant of both [3H]mazindol and [3H]GBR 12783 for their specific sites of binding present in membrane suspensions obtained from either rabbit or rat striatum. However, maximal concentrations of binding sites were not affected by temperature. At all tested temperatures, both substrates and carrier blockers competed with either [3H]mazindol or [3H]GBR 12783 in a monophasic fashion, with Hill coefficients close to unity. Raising the temperature induced little or no increase in inhibition constants (Ki) for substrates (Ki ratio 37/0 degrees C less than 2.5). This is consistent with the mild increase of the Michaelis constant of dopamine for the neuronal uptake system when the incubation temperature was raised from 12.5 to 37 degrees C (from 126 to 406 nM). In contrast, increasing the temperature resulted in a more important increase in the Ki of uptake inhibitors (33 greater than Ki ratio greater than 5). Thermodynamic calculations showed that the binding of substrates is generally characterized by a mild decrease in enthalpy (range, -2- -6 kcal/mol) associated with an increase in entropy, whereas binding of uptake inhibitors led to a decrease of both parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J J Bonnet
- Laboratoire de Neuropsychopharmacologie, Centre National de la Recherche Scientifique, Saint Etienne du Rouvray, France
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Vaugeois JM, Bonnet JJ, Costentin J. Relationship between the effects of dexamphetamine on locomotion and on striatal [3H]GBR 12783 binding in vivo. Eur J Pharmacol 1990; 178:221-7. [PMID: 2328762 DOI: 10.1016/0014-2999(90)90478-o] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In mice, low doses (1-2-4 mg/kg s.c.) of dexamphetamine stimulated locomotor activity in a dose-dependent manner. Over the same range of doses the drug dose dependently inhibited the in vivo striatal binding of the dopamine uptake inhibitor, [3H]GBR 12783. At 3 mg/kg dexamphetamine, the stimulant effect and the inhibition of the striatal binding of [3H]GBR 12783 displayed a similar time course. Pretreatments that either increased (L-DOPA 200 mg/kg, benserazide 50 mg/kg i.p.) or decreased (reserpine 5 mg/kg s.c., alpha-methyl-p-tyrosine 200 mg/kg) striatal dopamine levels did not modify the inhibition by dexamphetamine of [3H]GBR 12783 binding in vivo. This suggests that the inhibition is due to a direct effect of dexamphetamine, not mediated by endogenous dopamine, and further that a unique site is responsible for the neuronal uptake of dexamphetamine and for the binding of pure dopamine uptake inhibitors.
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Affiliation(s)
- J M Vaugeois
- Unité de Neuropsychopharmacologie Expérimentale, U.R.A. 1170 du CNRS, Faculté de Médecine et de Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Valchár M, Bonnet JJ, Costentin J. Chronic modification of dopaminergic transmission and its effects on binding characteristics of dopamine transporter ligand 3H-GBR 12783 in the striatum. Act Nerv Super (Praha) 1989; 31:273-4. [PMID: 2561622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M Valchár
- Research Institute for Pharmacy and Biochemistry, Prague, Czechoslovakia
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Cazanoue M, Lugan N, Bonnet JJ, Mathieu R. Additions and Corrections - Synthesis and Reacticity of [PPh4]-[MRu3Cp(CO)12]Clusters (M=Mo, W). Organometallics 1989. [DOI: 10.1021/om00114a602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Thibaut F, Bonnet JJ, Costentin J. Time course of postmortem modifications in synaptosomal [3H]dopamine uptake and [3H]GBR 12783 binding to the dopamine uptake complex in the rat striatum. Neurosci Lett 1989; 96:335-9. [PMID: 2717059 DOI: 10.1016/0304-3940(89)90401-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The present study focuses on the changes of two biochemical markers of the striatal dopaminergic innervation evaluated after different postmortem storage periods of rat heads either at room temperature (21 degrees C) or at 4 degrees C: (i) the uptake of [3H]dopamine (DA) into striatal synaptosomes and (ii) the specific binding of [3H]GBR 12783, a selective ligand for the neuronal dopamine uptake sites, to a striatal membrane fraction. The uptake of [3H]DA was completely abolished after 24 and 72 h storage of the tissue at 21 degrees C and 4 degrees C, respectively, whereas in the same conditions, the binding of [3H]GBR 12783 was slightly decreased. The Km and Kd of these two processes were virtually unchanged after the different storage periods considered, whereas the Vmax and Bmax were markedly decreased.
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Affiliation(s)
- F Thibaut
- Unité de Neuropsychopharmacologie expérimentale, C.N.R.S., U.A. 1170, U.F.R. de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France
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Abstract
The development of the specific uptake of dopamine in the rat striatum during the early postnatal period is compared with the ontogenetic changes of the specific binding of (3H)GBR 12783 to the site of uptake inhibition. During maturation, the increase in the specific binding of (3H)GBR 12783 parallels the increase in the specific uptake of dopamine. (3H)GBR 12783 specific binding sites increase in number from day 1 postpartum until 40 days, when they reach the adult level. In 40 day-old rats, the weight of the striatum represents 80% of adult values. The affinity of (3H)GBR 12783 for the inhibition site is similar in membrane preparations obtained from 6 day-old pups and adults; this results in a same ability of the inhibitor to block the specific uptake of dopamine into synaptosomes obtained from pups or adult rats. These data support the hypothesis of the existence of a single molecular entity including both the inhibition site and the carrier itself.
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Affiliation(s)
- J J Bonnet
- U.A. 1170 du C.N.R.S., U.E.R. de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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Bonnet JJ, Benmansour S, Vaugeois JM, Costentin J. Ionic requirements for the specific binding of [3H]GBR 12783 to a site associated with the dopamine uptake carrier. J Neurochem 1988; 50:759-65. [PMID: 3339350 DOI: 10.1111/j.1471-4159.1988.tb02979.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
At 0 degrees C, when Na+ was the only cation present in the incubation medium, increasing the Na+ concentration from 3 to 10 mM enhanced the affinity of [3H]1-[2-(++di-phenylmethoxy)ethyl]-4-(3-phenyl-2-propenyl)piperaz ine [( 3H]GBR 12783) for the specific binding site present in rat striatal membranes without affecting the Bmax. For higher Na+ concentrations, specific binding values plateaued and then slightly decreased at 130 mM Na+. In a 10 mM Na+ medium, the KD and the Bmax were, respectively, 0.23 nM and 12.9 pmol/mg of protein. In the presence of 0.4 nM [3H]GBR 12783, the half-maximal specific binding occurred at 5 mM Na+. A similar Na+ dependence was observed at 20 degrees C. Scatchard plots indicated that K+, Ca2+, Mg2+, and Tris+ acted like competitive inhibitors of the specific binding of [3H]GBR 12783. The inhibitory potency of various cations (K+, Ca2+, Mg2+, Tris+, Li+, and choline) was enhanced when the Na+ concentration was decreased from 130 to 10 mM. In a 10 mM Na+ medium, the rank order of inhibitory potency was Ca2+ (0.13 mM) greater than Mg2+ greater than Tris+ greater than K+ (15 mM). The requirement for Na+ was rather specific, because none of the other cations acted as a substitute for Na+. No anionic requirement was found: Cl-, Br-, and F- were equipotent. These results suggest that low Na+ concentrations are required for maximal binding; higher Na+ concentrations protect the specific binding site against the inhibitory effect of other cations.
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Affiliation(s)
- J J Bonnet
- UA 1170 du CNRS, UER de Médecine et Pharmacie, Saint Etienne du Rouvray, France
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Bonnet JJ, Chagraoui A, Protais P, Costentin J. Interactions of amineptine with the neuronal dopamine uptake system: neurochemical in vitro and in vivo studies. J Neural Transm (Vienna) 1987; 69:211-20. [PMID: 3625193 DOI: 10.1007/bf01244342] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effects of amineptine on 3H-dopamine uptake and 14C-dopamine release have been studied simultaneously in double labelling test performed on rat striatal synaptosomes. 3H-dopamine uptake was completely inhibited at 10 microM amineptine, a concentration which produced only a weak 14C-DA release (13% of the 14C-radioactivity stored). The IC 50 for the inhibition of 3H-DA uptake was not modified by a previous treatment with reserpine whereas the IC 50 of (+) amphetamine and the IC 50 of clomipramine were decreased 9 fold and increased two fold, respectively. In binding studies on rat striatal membranes amineptine displaces in vitro the 3H-GBR 12783, bound specifically to a component of the neuronal DA uptake complex. The apparent affinity of amineptine for this binding site was more than 150 times higher than its affinity for the binding site of 3H-desipramine on rat cortical membranes. In mice, increasing doses of amineptine injected i.p. reduced in a dose dependent manner the specific retention of radioactivity in the striatum after an i.v. injection of a tracer dose of 3H-GBR 12783. These data indicate that amineptine inhibits DA uptake and is virtually devoid of DA releasing effects. It displays a relatively low affinity for the NE uptake system. Its neurochemical profile in the double labelling test clearly differs from that of (+) amphetamine and from that of classical tricyclic anti-depressants.
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Abstract
[3H]GBR 12783 (1,2-(diphenylmethoxy)ethyl-4-(3-phenyl-2-propenyl)-piperazine), a specific dopamine uptake inhibitor, was tested for in vivo central binding in mice. The difference between the striatal and cerebellar levels of radioactivity was maximal 1 hour after the i.v. injection of a tracer dose of [3H]GBR 12783. The additional accumulation of radioactivity in striatum, relatively to cerebellum, was dose-dependently decreased by dopamine uptake inhibitors. It was unaffected by high doses of dopamine receptor agonists or antagonists and of serotonin or norepinephrine uptake blockers. The intrastriatal injection of 6-hydroxydopamine (6-OHDA) resulted in an almost similar decrease in both the synaptosomal [3H]dopamine uptake and the in vivo [3H]GBR 12783 binding. These data suggest that [3H]GBR 12783 injected i.v. labels the dopamine transport complex in the striatum and thus can be used for the in vivo assessment of the density of dopaminergic nerve endings in brain areas.
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Benmansour S, Bonnet JJ, Protais P, Costentin J. Sodium independence of the binding of [3H]GBR 12783 and other dopamine uptake inhibitors to the dopamine uptake complex. Neurosci Lett 1987; 77:97-102. [PMID: 3601221 DOI: 10.1016/0304-3940(87)90614-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
When Na+ was the only cation present in the incubation medium used for the determination of the specific binding of [3H]GBR 12783 in rat striatal membranes, the Na+-dependence between 10 and 210 mM Na+ was not observed. In media with low (10 mM) or high (130 mM) Na+ concentration, mazindol and nomifensine competed with [3H]GBR 12783 for its specific binding site with the same affinities. With the exception of amineptine, all the tested catecholamine uptake inhibitors were equally potent to compete with [3H]GBR 12783 when Na+ concentration was decreased from 130 to 10 mM. These data suggest that the media previously used for the binding studies of tritiated inhibitors of dopamine uptake (Tris-ions buffer and Krebs-Ringer medium) contain ions which could exert inhibitory effects on the specific binding at low Na+ concentration.
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Lavigne G, Lugan N, Bonnet JJ. Intermolecular association of cyanide substituted triruthenium carbonyl cluster anions: synthesis and crystal structure of [ppn]2[Ru6(CN)2(CO)20][ppn = bis(triphenylphosphine)iminium cation]. ACTA ACUST UNITED AC 1987. [DOI: 10.1039/c39870000957] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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