1
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Characterization of dopamine D 2 receptor coupling to G proteins in postmortem brain of subjects with schizophrenia. Pharmacol Rep 2021; 73:1136-1146. [PMID: 34196951 PMCID: PMC8413194 DOI: 10.1007/s43440-021-00305-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/16/2021] [Accepted: 06/24/2021] [Indexed: 11/04/2022]
Abstract
Background Alterations of dopamine D1 (D1R) and D2 receptor (D2R) are proposed in schizophrenia but brain neuroimaging and postmortem studies have shown controversial results in relation to D1R and D2R density. Besides, scarce information on the functionality of brain D1R and D2R is available. The present study characterized G-protein activation by D1R and D2R agonists in postmortem human brain. Furthermore, D2R functional status was compared between schizophrenia and control subjects. Methods G-protein receptor coupling was assessed in control caudate nucleus and frontal cortex by [35S]GTPγS-binding stimulation induced by increasing concentrations (10–10–10–3 M) of dopamine, and the selective dopaminergic agonists SKF38393 (D1R) and NPA (D2R). Concentration–response curves to NPA stimulation of [35S]GTPγS binding were analyzed in antipsychotic-free (n = 10) and antipsychotic-treated (n = 7) schizophrenia subjects and matched controls (n = 17). Results In caudate, [35S]GTPγS-binding responses to agonists were compatible with the existence of functional D2R. In contrast, stimulations in cortex showed responses that did not correspond to D1R or D2R. [35S]GTPγS-binding activation by NPA in caudate displayed biphasic curves with similar profile in schizophrenia (EC50H = 7.94 nM; EC50L = 7.08 μM) and control (EC50H = 7.24 nM; EC50L = 15.14 μM) subjects. The presence or absence of antipsychotic medication did not influence the pharmacological parameters. Conclusions Feasibility of functional evaluation of dopamine receptors in postmortem human brain by conventional [35S]GTPγS-binding assays appears to be restricted to signalling through inhibitory Gi/o proteins. These findings provide functional information about brain D2R status in subjects with schizophrenia and do not support the existence of D2R supersensitive in this mental disorder. Supplementary Information The online version contains supplementary material available at 10.1007/s43440-021-00305-4.
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2
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Odagaki Y, Kinoshita M, Ota T, Meana JJ, Callado LF, García-Sevilla JA. Optimization and pharmacological characterization of receptor-mediated G i/o activation in postmortem human prefrontal cortex. Basic Clin Pharmacol Toxicol 2019; 124:649-659. [PMID: 30507034 DOI: 10.1111/bcpt.13183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/22/2018] [Indexed: 01/11/2023]
Abstract
The biochemical abnormalities in transmembrane signal transduction mediated through G protein-coupled receptors (GPCRs) have been postulated as underlying pathophysiology of psychiatric diseases such as schizophrenia and mood disorders. In the present study, the experimental conditions of agonist-induced [35 S]GTPγS binding in postmortem human brain membranes were optimized, and the responses induced by a series of agonists were pharmacologically characterized. The [35 S]GTPγS binding assay was performed in postmortem human prefrontal cortical membranes by means of filtration techniques, and standardized as to GDP concentration, membrane protein content, MgCl2 and NaCl concentrations in assay buffer, incubation period and effect of white matter contamination. Under the standard assay conditions, the specific [35 S]GTPγS binding was stimulated by the addition of 15 compounds in a concentration-dependent manner. Of these agonists, R(+)-8-OH-DPAT, UK-14,304, DAMGO and DPDPE showed apparently biphasic concentration-response curves. As for these four responses, only higher-potency site was pharmacologically characterized. The receptors involved in the responses investigated were 5-HT1A receptor (probed with R(+)-8-OH-DPAT or 5-HT), α2A -adrenoceptor (UK-14,304 or (-)-epinephrine), M2 /M4 mAChRs (carbachol), adenosine A1 receptor (adenosine), histamine H3 receptor (histamine), group II mGlu (l-glutamate), GABAB receptor (baclofen), μ-opioid receptor (DAMGO or endomophin-1), δ-opioid receptor (DPDPE or SNC-80) and NOP (nociceptin). Although dopamine also activated specific [35 S]GTPγS binding, this response was likely mediated via α2A -adrenoceptor, but not dopamine receptor subtypes. The present study provides us with fundamental aspects of the strategy for elucidation of probable abnormalities of neural signalling mediated by G proteins activated through multiple GPCRs in the brain of psychiatric patients.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Binding, Competitive
- Female
- GTP-Binding Proteins/agonists
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Male
- Middle Aged
- Prefrontal Cortex/metabolism
- Protein Binding
- Receptor, Adenosine A1/metabolism
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, GABA-B/metabolism
- Receptors, Histamine H3/metabolism
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, Opioid, mu/metabolism
- Receptors, sigma/metabolism
- Young Adult
- Sigma-1 Receptor
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Affiliation(s)
- Yuji Odagaki
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Masakazu Kinoshita
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Toshio Ota
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - J Javier Meana
- Department of Pharmacology, University of the Basque Country, UPV/EHU, Leioa, Bizkaia
- Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Luis F Callado
- Department of Pharmacology, University of the Basque Country, UPV/EHU, Leioa, Bizkaia
- Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Jesús A García-Sevilla
- Laboratory of Neuropharmacology, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), University of the Balearic Islands (UIB), Balearic Islands Health Research Institute (IdISBa), Palma de Mallorca, Spain
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3
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Napolitano F, D'Angelo L, de Girolamo P, Avallone L, de Lange P, Usiello A. The Thyroid Hormone-target Gene Rhes a Novel Crossroad for Neurological and Psychiatric Disorders: New Insights from Animal Models. Neuroscience 2018; 384:419-428. [PMID: 29857029 DOI: 10.1016/j.neuroscience.2018.05.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 02/08/2023]
Abstract
Ras homolog enriched in striatum (Rhes) is predominantly expressed in the corpus striatum. Rhes mRNA is localized in virtually all dopamine D1 and D2 receptor-bearing medium-sized spiny neurons (MSNs), and cholinergic interneurons of striatum. Early studies in rodents showed that Rhes is developmentally regulated by thyroid hormone, as well as by dopamine innervation in adult rat, monkey and human brains. At cellular level, Rhes interferes with adenosine A2A- and dopamine D1 receptor-dependent cAMP/PKA pathway, upstream of the activation of the heterotrimeric G protein complex. Besides its involvement in GPCR-mediated signaling, Rhes modulates Akt pathway activation, acts as E3-ligase of mutant huntingtin, whose sumoylation accounts for neurotoxicity in Huntington's disease, and physically interacts with Beclin-1, suggesting its potential involvement in autophagy-related cellular events. In addition, this protein can also bind to and activate striatal mTORC1, one of the key players in l-DOPA-induced dyskinesia in rodent models of Parkinson's disease. Accordingly, lack of Rhes attenuated such motor disturbances in 6-OHDA-lesioned Rhes knockout mice. In support of its role in MSN-dependent functions, several studies documented that mutant animals displayed alterations in striatum-related phenotypes reminiscent of psychiatric illness in humans, including deficits in prepulse inhibition of startle reflex and, most interestingly, a striking enhancement of behavioral responses elicited by caffeine, phencyclidine or amphetamine. Overall, these data suggest that Rhes modulates molecular and biochemical events underlying striatal functioning, both in physiological and pathological conditions.
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Affiliation(s)
- Francesco Napolitano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy; Ceinge Biotecnologie Avanzate, Naples, Italy.
| | - Livia D'Angelo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy; Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Paolo de Girolamo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Luigi Avallone
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Pieter de Lange
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy
| | - Alessandro Usiello
- Ceinge Biotecnologie Avanzate, Naples, Italy; Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy.
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Koener B, Goursaud S, Van De Stadt M, Calas AG, Jeanjean AP, Maloteaux JM, Hermans E. Pharmacological blockade of dopamine D2 receptors by aripiprazole is not associated with striatal sensitization. Naunyn Schmiedebergs Arch Pharmacol 2011; 383:65-77. [PMID: 21061116 DOI: 10.1007/s00210-010-0577-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 10/25/2010] [Indexed: 11/26/2022]
Abstract
The partial agonist profile of novel antipsychotics such as aripiprazole has hardly been demonstrated in biochemical assays on animal tissues. As it is established that responses induced by dopamine D₂ receptor agonists are increased in models of dopaminergic sensitization, this paradigm was used in order to facilitate the detection of the partial agonist properties of aripiprazole. At variance with all other partial and full agonists tested, the partial agonist properties of aripiprazole were not revealed in guanosine 5′-O-(γ-[³⁵S]thiotriphosphate ([³⁵S]GTPγS) binding assays on striatal membranes from haloperidol-treated rats. Hence,aripiprazole behaved as an antagonist, efficiently inhibiting the functional response to dopamine. Similarly, in behavioural assays, aripiprazole dose-dependently inhibited the stereotypies elicited by apomorphine. However, at variance with haloperidol, repeated administrations of aripiprazole(3 weeks) at the doses of 10 and 30 mg/kg did not induce any up-regulation or hyperfunctionality of the dopamine D₂ receptors in the striatum. These data highlight the putative involvement of other pharmacological targets for aripiprazole that would support in the prevention of secondary effects commonly associated with the blockade of striatal dopamine D₂ receptors. Hence, in additional experiments, aripiprazole was found to efficiently promote [³⁵S]GTPγS binding in hippocampal membranes through the activation of 5-HT(₁A) receptors. Further experiments investigating the second messenger cascades should be performed so as to establish the functional properties of aripiprazole and understand the mechanism underlying the prevention of dopamine receptor regulation in spite of the observed antagonism.
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Affiliation(s)
- Beryl Koener
- Institute of Neurosciences (IoNS), Group of Neuropharmacology, Université Catholique de Louvain, Brussels, Belgium
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5
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Napolitano F, Pasqualetti M, Usiello A, Santini E, Pacini G, Sciamanna G, Errico F, Tassone A, Di Dato V, Martella G, Cuomo D, Fisone G, Bernardi G, Mandolesi G, Mercuri NB, Standaert DG, Pisani A. Dopamine D2 receptor dysfunction is rescued by adenosine A2A receptor antagonism in a model of DYT1 dystonia. Neurobiol Dis 2010; 38:434-45. [PMID: 20227500 DOI: 10.1016/j.nbd.2010.03.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/04/2010] [Accepted: 03/04/2010] [Indexed: 11/27/2022] Open
Abstract
DYT1 dystonia is an inherited disease linked to mutation in the TOR1A gene encoding for the protein torsinA. Although the mechanism by which this genetic alteration leads to dystonia is unclear, multiple lines of clinical evidence suggest a link between dystonia and a reduced dopamine D2 receptor (D2R) availability. Based on this evidence, herein we carried out a comprehensive analysis of electrophysiological, behavioral and signaling correlates of D2R transmission in transgenic mice with the DYT1 dystonia mutation. Electrophysiological recordings from nigral dopaminergic neurons showed a normal responsiveness to D2-autoreceptor function. Conversely, postsynaptic D2R function in hMT mice was impaired, as suggested by the inability of a D2R agonist to re-establish normal corticostriatal synaptic plasticity and supported by the reduced sensitivity to haloperidol-induced catalepsy. Although an in situ hybridization analysis showed normal D1R and D2R mRNA expression levels in the striata of hMT mice, we found a significant decrease of D2R protein, coupled to a reduced ability of D2Rs to activate their cognate Go/i proteins. Of relevance, we found that pharmacological blockade of adenosine A2A receptors (A2ARs) fully restored the impairment of synaptic plasticity observed in hMT mice. Together, our findings demonstrate an important link between torsinA mutation and D2R dysfunction and suggest that A2AR antagonism is able to counteract the deficit in D2R-mediated transmission observed in mutant mice, opening new perspectives for the treatment of this movement disorder.
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6
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Abstract
The Tokyo Metropolitan Government in Japan enacted an "Ordinance concerning the abuse prevention of the psychoactive drugs" in April 2006 that prohibited the manufacture, cultivation, sales, possession, use, etc., of these drugs. Therefore, we constructed a reproducible, simple, and small-scale determination method of the psychoactive drugs for the re-uptake and the release of monoamines (dopamine, serotonin and norepinephrine), and the activation of [(35)S]guanosine-5'-O-(3-thio)-triphosphate binding to guanine nucleotide-binding proteins (G proteins). These assays were then applied to study the effects of different kinds (phenethylamine derivatives, tryptamine derivatives, and piperazine derivatives) of non-medically used psychoactive drugs on monoamine re-uptake and release, and G-protein binding. The results suggested that some drugs strongly act on the central nerve system to the same extent as the drugs. This assay system was able to designate psychoactive drugs as prohibited substances in accordance with criteria set forth by the Tokyo Metropolitan government.
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Affiliation(s)
- Kanako Satoh
- Department of Environmental Health and Toxicology, Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
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7
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Nonaka R, Nagai F, Ogata A, Satoh K. In vitro screening of psychoactive drugs by [(35)S]GTPgammaS binding in rat brain membranes. Biol Pharm Bull 2008; 30:2328-33. [PMID: 18057721 DOI: 10.1248/bpb.30.2328] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We constructed a reproducible, simple, and small-scale determination method of the psychoactive drugs that acted directly on the monoamine receptor by measuring the activation of [(35)S]guanosine-5'-O-(3-thio)-triphosphate binding to guanine nucleotide-binding proteins (G proteins). This method can simultaneously measure the effects of three monoamines, namely dopamine (DA), serotonin (5-HT), and norepinephrine (NE), in rat brain membranes using a 96-well microplate. Activation of D(1) and D(2) receptors in striatal membranes by DA as well as 5-HT and NEalpha(2) receptors in cortical membranes could be measured. Of 12 tested phenethylamines, 2,5-dimethoxy-4-chlorophenethylamine (2C-C), 2,5-dimethoxy-4-ethylphenethylamine (2C-E), and 2,5-dimethoxy-4-iodophenethylamine (2C-I) stimulated G protein binding. The other phenethylamines did not affect G protein binding. All 7 tryptamines tested stimulated G protein binding with the following rank order of potency; 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT)>5-methoxy-N,N-diallyltryptamine (5-MeO-DALT)>5-methoxy-alpha-methyltryptamine (5-MeO-AMT)>or=5-methoxy-N,N-methylisopropyltryptamine (5-MeO-MIPT)>5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT)>N,N-dipropyltryptamine (DPT)>or=alpha-methyltryptamine (AMT). This assay system was able to designate psychoactive drugs as prohibited substances in accordance with criteria set forth by the Tokyo Metropolitan government.
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Affiliation(s)
- Ryouichi Nonaka
- Department of Environmental Health and Toxicology, Tokyo Metropolitan Institute of Public Health, 3-24-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan.
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8
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Errico F, Santini E, Migliarini S, Borgkvist A, Centonze D, Nasti V, Carta M, De Chiara V, Prosperetti C, Spano D, Herve D, Pasqualetti M, Di Lauro R, Fisone G, Usiello A. The GTP-binding protein Rhes modulates dopamine signalling in striatal medium spiny neurons. Mol Cell Neurosci 2007; 37:335-45. [PMID: 18035555 DOI: 10.1016/j.mcn.2007.10.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 10/11/2007] [Accepted: 10/16/2007] [Indexed: 11/27/2022] Open
Abstract
Rhes is a small GTP-binding protein prominently localized in the striatum. Previous findings obtained in cell culture systems demonstrated an involvement of Rhes in cAMP/PKA signalling pathway, at a level proximal to the activation of heterotrimeric G-protein complex. However, its role in the striatum has been, so far, only supposed. Here we studied the involvement of Rhes in dopaminergic signalling, by employing mice with a null mutation in the Rhes gene. We demonstrated that the absence of Rhes modulates cAMP/PKA signalling in both striatopallidal and striatonigral projection neurons by increasing Golf protein levels and, in turn, influencing motor responses challenged by dopaminergic agonist/antagonist. Interestingly, we also show that Rhes is required for a correct dopamine-mediated GTP binding, a function mainly associated to stimulation of dopamine D2 receptors. Altogether, our results indicate that Rhes is an important modulator of dopaminergic transmission in the striatum.
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9
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Centonze D, Rossi S, Napoli I, Mercaldo V, Lacoux C, Ferrari F, Ciotti MT, De Chiara V, Prosperetti C, Maccarrone M, Fezza F, Calabresi P, Bernardi G, Bagni C. The brain cytoplasmic RNA BC1 regulates dopamine D2 receptor-mediated transmission in the striatum. J Neurosci 2007; 27:8885-92. [PMID: 17699670 PMCID: PMC6672174 DOI: 10.1523/jneurosci.0548-07.2007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 06/07/2007] [Accepted: 06/22/2007] [Indexed: 11/21/2022] Open
Abstract
Dopamine D(2) receptor (D(2)DR)-mediated transmission in the striatum is remarkably flexible, and changes in its efficacy have been heavily implicated in a variety of physiological and pathological conditions. Although receptor-associated proteins are clearly involved in specific forms of synaptic plasticity, the molecular mechanisms regulating the sensitivity of D(2) receptors in this brain area are essentially obscure. We have studied the physiological responses of the D(2)DR stimulations in mice lacking the brain cytoplasmic RNA BC1, a small noncoding dendritically localized RNA that is supposed to play a role in mRNA translation. We show that the efficiency of D(2)-mediated transmission regulating striatal GABA synapses is under the control of BC1 RNA, through a negative influence on D(2) receptor protein level affecting the functional pool of receptors. Ablation of the BC1 gene did not result in widespread dysregulation of synaptic transmission, because the sensitivity of cannabinoid CB(1) receptors was intact in the striatum of BC1 knock-out (KO) mice despite D(2) and CB(1) receptors mediated similar electrophysiological actions. Interestingly, the fragile X mental retardation protein FMRP, one of the multiple BC1 partners, is not involved in the BC1 effects on the D(2)-mediated transmission. Because D(2)DR mRNA is apparently equally translated in the BC1-KO and wild-type mice, whereas the protein level is higher in BC1-KO mice, we suggest that BC1 RNA controls D(2)DR indirectly, probably regulating translation of molecules involved in D(2)DR turnover and/or stability.
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MESH Headings
- Animals
- Animals, Newborn
- Biphenyl Compounds/pharmacology
- Cells, Cultured
- Corpus Striatum/cytology
- Dopamine D2 Receptor Antagonists
- Glutamate Decarboxylase/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacokinetics
- In Vitro Techniques
- Inhibitory Postsynaptic Potentials/drug effects
- Inhibitory Postsynaptic Potentials/physiology
- Isoenzymes/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microtubule-Associated Proteins/metabolism
- Neurons/drug effects
- Neurons/physiology
- Oligonucleotides/pharmacology
- Patch-Clamp Techniques/methods
- Piperazines/pharmacology
- RNA, Long Noncoding
- RNA, Messenger/biosynthesis
- RNA, Untranslated
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/physiology
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Ribonucleoproteins, Small Cytoplasmic/deficiency
- Ribonucleoproteins, Small Cytoplasmic/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- Diego Centonze
- Clinica Neurologica, Dipartimento di Neuroscienze
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Silvia Rossi
- Clinica Neurologica, Dipartimento di Neuroscienze
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Ilaria Napoli
- Dipartimento di Biologia, and
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Valentina Mercaldo
- Dipartimento di Biologia, and
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Caroline Lacoux
- Dipartimento di Biologia, and
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Francesca Ferrari
- Dipartimento di Biologia, and
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Maria Teresa Ciotti
- Dipartimento di Biologia, and
- Consiglio Nazionale delle Ricerche/CERC, 00143 Rome, Italy
| | - Valentina De Chiara
- Clinica Neurologica, Dipartimento di Neuroscienze
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Chiara Prosperetti
- Clinica Neurologica, Dipartimento di Neuroscienze
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Mauro Maccarrone
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
- Dipartimento di Scienze Biomediche Comparate, Università degli Studi di Teramo, 64100 Teramo, Italy, and
| | - Filomena Fezza
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università Tor Vergata, 00133 Rome, Italy
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Paolo Calabresi
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
- Clinica Neurologica, Università di Perugia, Ospedale Silvestrini, 06156 Perugia, Italy
| | - Giorgio Bernardi
- Clinica Neurologica, Dipartimento di Neuroscienze
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
| | - Claudia Bagni
- Dipartimento di Biologia, and
- Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), 00143 Rome, Italy
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Dopamine D2 receptor-mediated G protein activation assessed by agonist-stimulated [35S]guanosine 5'-O-(gamma-thiotriphosphate) binding in rat striatal membranes. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:1304-12. [PMID: 16824659 DOI: 10.1016/j.pnpbp.2006.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 05/09/2006] [Accepted: 05/09/2006] [Indexed: 11/29/2022]
Abstract
In order to investigate the functional interaction between the native dopamine receptors and their coupled guanine nucleotide-binding regulatory (G) proteins, dopamine-stimulated [(35)S]guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding was pharmacologically characterized in rat striatal membranes. Following optimizing the experimental conditions as to the concentrations of GDP, MgCl(2) and NaCl in the assay medium, the agonist and antagonist properties for a series of dopamine receptor ligands were determined mainly under the standard assay condition. The pharmacological profile of this response clearly indicated the involvement of dopamine D(2)-like receptors, but not of dopamine D(1)-like receptors. Among the types of dopamine D(2)-like receptors, dopamine D(2) receptors most likely appeared to be involved in dopamine-stimulated [(35)S]GTPgammaS binding in rat striatal membranes, because the affinities of agonists and antagonists determined in the present study were significantly correlated with those reported in the previous literature only for dopamine D(2) receptors, but not for dopamine D(3) or D(4) types. Though the concentration-dependent inhibition curves of dopamine-stimulated [(35)S]GTPgammaS binding by spiperone and S(-)-raclopride were apparently biphasic, the origin of the low-affinity minor components was not fully determined. The antiparkinsonian drugs with the properties of dopamine receptor agonism were shown to behave as stimulants with varied affinities and relative efficacies in the current assay system. On the other hand, neither phencyclidine (PCP) nor ketamine stimulated the specific [(35)S]GTPgammaS binding, in contrast with the previous report demonstrating that these two N-methyl-D-aspartic acid (NMDA) receptor antagonists behaved as agonists at human dopamine D(2) receptors expressed in Chinese hamster ovary (CHO) cells. These results provide important information about the functional activation of G proteins coupled with dopamine D(2) receptors as well as agonist actions of various compounds at native dopamine D(2) receptors, which are potentially involved in pathophysiology and pharmacotherapy of neuropsychiatric diseases such as Parkinson's disease, schizophrenia and depression.
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11
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Jordan S, Chen R, Fernalld R, Johnson J, Regardie K, Kambayashi J, Tadori Y, Kitagawa H, Kikuchi T. In vitro biochemical evidence that the psychotomimetics phencyclidine, ketamine and dizocilpine (MK-801) are inactive at cloned human and rat dopamine D2 receptors. Eur J Pharmacol 2006; 540:53-6. [PMID: 16730695 DOI: 10.1016/j.ejphar.2006.04.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 04/21/2006] [Accepted: 04/25/2006] [Indexed: 11/24/2022]
Abstract
Dopamine potently increased calcium mobilization in Chinese hamster ovary cells expressing human dopamine D2Long receptors (CHO-D2L cells), and increased guanosine-5'-O-(3-[35S]thio)-triphosphate binding to CHO-D2L cell and rat striatal membranes. These effects of dopamine were blocked by the dopamine D2 receptor antagonist (-)raclopride. In contrast to the findings of a recent controversial study, phencyclidine, ketamine and dizocilpine (MK-801) lacked dopamine D2 receptor full agonist, partial agonist and antagonist activity in these assays, suggesting their psychotomimetic effects, and activity in rodent models of schizophrenia, are associated with N-methyl-d-aspartate receptor blockade rather than a direct interaction with dopamine D2 receptors.
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Affiliation(s)
- Shaun Jordan
- Department of Neuroscience Research, Otsuka Maryland Medicinal Laboratories, 9900, Medical Center Drive, Rockville, MD 20850, USA.
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Panchalingam S, Undie AS. Physicochemical modulation of agonist-induced [35s]GTPgammaS binding: implications for coexistence of multiple functional conformations of dopamine D1-like receptors. J Recept Signal Transduct Res 2005; 25:125-46. [PMID: 16149770 DOI: 10.1080/10799890500184948] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Dopamine agonist-stimulated [35S]GTPgammaS binding to membrane G proteins was studied in select brain regions under experimental conditions that permit the activation of receptor coupling to the G proteins Gi, Gs, or Gq. Agents studied were agonists known to be effective at various dopamine receptor/effector systems and included quinelorane (D2-like/Gi), SKF38393 (D1-like/Gq, D1-like/Gs), SKF85174 (D1-like/Gs), and SKF83959 (D1-like/Gq). Dopamine and SKF38393 significantly stimulated [35S]GTPgammaS binding to normal striatal membranes by 161% and 67% above controls. Deoxycholate, which enhances agonist-induced phospholipase C (PLC) stimulation, markedly enhanced the agonistic effects of dopamine and SKF38393 to 530% and 637% above controls, respectively. The enhancing effects of deoxycholate were reversed if it was washed off the membranes before agonist addition. The thiol-reducing agent, dithiothreitol, completely abolished the effects of SKF38393 and SKF83959, whereas SKF85174 effects were augmented. Agonist responses were concentration-related, and highest efficacies were obtained in the hippocampus, thus paralleling both the brain regional distribution and agonist efficacies previously observed in phosphoinositide hydrolysis assays. These findings suggest that D1-like receptor conformations that mediate agonist stimulation of Gs/adenylylcyclase may be structurally different from those that mediate Gq/PLC activation. Although the exact mechanism of deoxycholate's effect awaits elucidation, the results are consistent with the emerging concept of functional selectivity whereby deoxycholate could create a membrane environment that facilitates the transformation of the receptor from a conformation that activates Gs/adenylylcyclase to one that favors Gq/PLC signaling.
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Affiliation(s)
- Sandra Panchalingam
- Neuropharmacology Laboratory, Department of Pharmaceutical Sciences, School of Pharmacy and The Program in Neuroscience, University of Maryland, Baltimore, Maryland 21201-1075, USA
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13
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Sóvágó J, Makkai B, Gulyás B, Hall H. Autoradiographic mapping of dopamine-D2/D3 receptor stimulated [35S]GTPgammaS binding in the human brain. Eur J Neurosci 2005; 22:65-71. [PMID: 16029196 DOI: 10.1111/j.1460-9568.2005.04192.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Agonist stimulated [35S]guanosine 5'-gamma-thiotriphosphate ([35S]GTPgammaS) binding autoradiography was established for the examination of dopamine-D2/D2 receptors in human brain sections. The distribution of G proteins activated by dopamine-D2/D3 receptors was studied in whole hemisphere cryosections. Dopamine stimulated [35S]GTPgammaS binding in brain regions with high densities of dopamine D2-like receptors, i.e. putamen (23 +/- 2%, mean +/- SEM,% stimulation over basal binding), caudate (20 +/- 0%) and substantia nigra (22 +/- 2%), but also in regions with lower receptor densities such as amygdala (17 +/- 8%), hippocampus (16 +/- 6%), anterior cingulate (13 +/- 3%), and thalamus (12 +/- 2%). Dopamine stimulated [35S]GTPgammaS binding to significantly higher levels in the dorsal than in the ventral part of the striatum. Dopamine caused low or very low stimulation in all cortical areas. Raclopride, a selective D2/D3 receptor antagonist, potently inhibited dopamine stimulated [35S]GTPgammaS binding, whereas R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390), a selective D1 antagonist, did not block the [35S]GTPgammaS binding response stimulated by dopamine. Hence, the stimulatory effect of dopamine was primarily mediated by D2/D3 receptors. Quinpirole stimulated [35S]GTPgammaS binding in the same regions as dopamine. The maximal level of stimulation induced by dopamine and quinpirole was not significantly different. The present study demonstrates that agonist stimulated [35S]GTPgammaS binding autoradiography could be a suitable technique for the examination of dopamine-D2/D3 receptors in the human brain. This functional assay could provide useful new information about dopamine receptor/G protein coupling in the postmortem human brain, and reveal possible disease related alterations of the interaction between D2/D3 receptors and G proteins.
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Affiliation(s)
- Judit Sóvágó
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176, Stockholm, Sweden
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14
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Bhattacharjee AK, Chang L, Lee HJ, Bazinet RP, Seemann R, Rapoport SI. D2 but not D1 dopamine receptor stimulation augments brain signaling involving arachidonic acid in unanesthetized rats. Psychopharmacology (Berl) 2005; 180:735-42. [PMID: 16163535 DOI: 10.1007/s00213-005-2208-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 01/18/2005] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES Signal transduction involving the activation of phospholipase A2 (PLA2) to release arachidonic acid (AA) from membrane phospholipids, when coupled to dopamine D1- and D2-type receptors, can be imaged in rats having a chronic unilateral lesion of the substantia nigra. It is not known, however, if the signaling responses occur in the absence of a lesion. To determine this, we used our in vivo fatty acid method to measure signaling in response to D1 and D2 receptor agonists given acutely to unanesthetized rats. METHODS [1-(14)C]AA was injected intravenously in unanesthetized rats, and incorporation coefficients k* for AA (brain radioactivity/integrated plasma radioactivity) were measured using quantitative autoradiography in 61 brain regions. The animals were administered i.v. the D2 receptor agonist, quinpirole (1 mg kg(-1), i.v.), the D1 receptor agonist SKF-38393 (5 mg kg(-1), i.v.), or vehicle/saline. RESULTS Quinpirole increased k* significantly in multiple brain regions rich in D2-type receptors, whereas SKF-38393 did not change k* significantly in any of the 61 regions examined. CONCLUSIONS In the intact rat brain, D2 but not D1 receptors are coupled to the activation of PLA2 and the release of AA.
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Affiliation(s)
- Abesh Kumar Bhattacharjee
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bldg. 9, Room 1S128, Bethesda, MD 20892, USA.
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15
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MacDonald AF, Billington CJ, Levine AS. Alterations in food intake by opioid and dopamine signaling pathways between the ventral tegmental area and the shell of the nucleus accumbens. Brain Res 2004; 1018:78-85. [PMID: 15262208 DOI: 10.1016/j.brainres.2004.05.043] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2004] [Indexed: 11/25/2022]
Abstract
Reward is an important factor motivating food intake in satiated animals. Two sites involved in the reward response are the ventral tegmental area (VTA) and the nucleus accumbens shell region (sNAcc), between which communication is partially regulated by opioids and dopamine (DA). Previous studies have shown that the mu-opioid agonist Tyr-D-Ala-Gly-MePhe-Gly(ol)-enkephalin (DAMGO) dose-dependently enhances food intake in satiated animals when injected into either the VTA or the sNAcc. The enhanced intake elicited by DAMGO injected into the sNAcc was dose-dependently blocked by injection of naltrexone (NTX) bilaterally into the VTA, indicating an opioid-dependent signaling pathway from the sNAcc to the VTA in mediation of food intake. In the present study, we cannulated animals bilaterally in both the VTA and the sNAcc to further study the nature of opioid- and DA-dependent communication between the sites. Food intake elicited by DAMGO (2 or 5 nmol) injected unilaterally into the VTA was dose-dependently diminished by bilateral injection of NTX (2.5, 5, and 25 g/side) or the D1 antagonist SCH 23390 (3, 1, 0.3, 0.15, 0.05, and 0.015 nmol/side) into the sNAcc. When DAMGO (5 nmol) was injected into the sNAcc, the resulting food intake was decreased by doses of SCH 23390 ranging from 0.05 to 100 nmol/side injected bilaterally into the VTA, but not by equimolar doses of Raclopride, a D2 antagonist. These results, combined with previous findings, suggest a signaling pathway between the VTA and the sNAcc in which opioids and DA facilitate feeding in an interdependent manner.
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Affiliation(s)
- Amy F MacDonald
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis 55415, USA
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16
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Carr KD, Tsimberg Y, Berman Y, Yamamoto N. Evidence of increased dopamine receptor signaling in food-restricted rats. Neuroscience 2003; 119:1157-67. [PMID: 12831870 DOI: 10.1016/s0306-4522(03)00227-6] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It is well established that chronic food restriction enhances sensitivity to the rewarding and motor-activating effects of abused drugs. However, neuroadaptations underlying these behavioral effects have not been characterized. The purpose of the present study was to explore the possibility that food restriction produces increased dopamine (DA) receptor function that is evident in behavior, signal transduction, and immediate early gene expression. In the first two experiments, rats received intracerebroventricular (i.c.v.) injections of the D1 DA receptor agonist SKF-82958, and the D2/3 DA receptor agonist quinpirole. Both agonists produced greater motor-activating effects in food-restricted than ad libitum-fed rats. In addition, Fos-immunostaining induced by SKF-82958 in caudate-putamen (CPu) and nucleus accumbens (Nac) was greater in food-restricted than ad libitum-fed rats, as was staining induced by quinpirole in globus pallidus and ventral pallidum. In the next two experiments, neuronal membranes prepared from CPu and Nac were exposed to SKF-82958 and quinpirole. Despite the documented involvement of cyclic AMP (cAMP) signaling in D1 DA receptor-mediated c-fos induction, stimulation of adenylyl cyclase (AC) activity by SKF-82958 in CPu and Nac did not differ between groups. Food restriction did, however, decrease AC stimulation by the direct enzyme stimulant, forskolin, but not NaF or MnCl(2), suggesting a shift in AC expression to a less catalytically efficient isoform. Finally, food restriction increased quinpirole-stimulated [(35)S]guanosine triphosphate-gammaS binding in CPu, suggesting that increased functional coupling between D2 DA receptors and G(i) may account for the augmented behavioral and pallidal c-Fos responses to quinpirole. Results of this study support the hypothesis that food restriction leads to neuroadaptations at the level of postsynaptic D1 and D2 receptor-bearing cells which, in turn, mediate augmented behavioral and transcriptional responses to DA. The signaling pathways mediating these augmented responses remain to be fully elucidated.
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Affiliation(s)
- K D Carr
- Department of Psychiatry, Millhauser Laboratories, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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17
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Peeters M, Maloteaux JM, Hermans E. Distinct effects of amantadine and memantine on dopaminergic transmission in the rat striatum. Neurosci Lett 2003; 343:205-9. [PMID: 12770697 DOI: 10.1016/s0304-3940(03)00398-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Striatal glutamatergic inputs are known to participate in the modulation of dopaminergic transmission. Accordingly, the non-competitive N-methyl-D-aspartate receptor antagonists memantine and amantadine increase striatal dopamine levels, the latter being widely used in Parkinson's disease therapy. Based on our previous work revealing increased function of dopamine receptors and dopamine transporter after amantadine treatment, we studied the effects of repeated memantine administration on dopaminergic neurotransmission. On rat striatal membranes, dopamine-stimulated [(35)S]GTPgammaS binding was significantly reduced (20%) after 2 days injection with memantine (20 mg/kg per day, i.p.) but not after longer treatments (4 or 7 days). Evaluation of [(3)H]SCH 23390 and [(3)H]spiperone specific bindings only revealed a significant increase in D1 receptor density after 4 or 7 days treatment. Finally, none of these treatments were found to change the activity of the neuronal dopamine transporter in striatal synaptosomes. This shows that amantadine and memantine differentially affect striatal dopaminergic transmission, which could indicate that these two related aminoadamantanes display distinct pharmacodynamic properties.
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Affiliation(s)
- Magali Peeters
- Laboratoire de Pharmacologie Expérimentale (FARL), Université Catholique de Louvain 54.10, Avenue Hippocrate 54, B-1200 Brussels, Belgium
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18
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Lindgren N, Usiello A, Goiny M, Haycock J, Erbs E, Greengard P, Hokfelt T, Borrelli E, Fisone G. Distinct roles of dopamine D2L and D2S receptor isoforms in the regulation of protein phosphorylation at presynaptic and postsynaptic sites. Proc Natl Acad Sci U S A 2003; 100:4305-9. [PMID: 12651945 PMCID: PMC153088 DOI: 10.1073/pnas.0730708100] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dopamine D2 receptors are highly expressed in the dorsal striatum where they participate in the regulation of (i) tyrosine hydroxylase (TH), in nigrostriatal nerve terminals, and (ii) the dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32), in medium spiny neurons. Two isoforms of the D2 receptor are generated by differential splicing of the same gene and are referred to as short (D2S) and long (D2L) dopamine receptors. Here we have used wild-type mice, dopamine D2 receptor knockout mice (D2 KO mice; lacking both D2S and D2L receptors) and D2L receptor-selective knockout mice (D2L KO mice) to evaluate the involvement of each isoform in the regulation of the phosphorylation of TH and DARPP-32. Incubation of striatal slices from wild-type mice with quinpirole, a dopamine D2 receptor agonist, decreased the state of phosphorylation of TH at Ser-40 and its enzymatic activity. Both effects were abolished in D2 KO mice but were still present in D2L KO mice. In wild-type mice, quinpirole inhibits the increase in DARPP-32 phosphorylation at Thr-34 induced by SKF81297, a dopamine D1 receptor agonist. This effect is absent in D2 KO as well as D2L KO mice. The inability of quinpirole to regulate DARPP-32 phosphorylation in D2L KO mice cannot be attributed to decreased coupling of D2S receptors to G proteins, because quinpirole produces a similar stimulation of [(35)S]GTPgammaS binding in wild-type and D2L KO mice. These results demonstrate that D2S and D2L receptors participate in presynaptic and postsynaptic dopaminergic transmission, respectively.
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Affiliation(s)
- Niklas Lindgren
- Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
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19
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Peeters M, Page G, Maloteaux JM, Hermans E. Hypersensitivity of dopamine transmission in the rat striatum after treatment with the NMDA receptor antagonist amantadine. Brain Res 2002; 949:32-41. [PMID: 12213297 DOI: 10.1016/s0006-8993(02)02961-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Amantadine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist known to increase dopamine synthesis and release in the striatum, is frequently associated with L-DOPA in the treatment of Parkinson's disease. However, the biochemical mechanisms involved in the effect of amantadine and the consequences of its repetitive administration on the modulation of striatal dopamine transmission still need to be clarified. We have investigated the effects of short-term amantadine treatments on the expression of dopamine receptors and the functional coupling to G proteins in rat striatal membranes. Dopamine-induced stimulation of guanosine 5'-[gamma-35S]triphosphate ([35S]GTPgammaS) binding was significantly enhanced (40%) in striatum homogenates from rats treated for 4 days with amantadine (40 mg/kg, i.p.) compared to vehicle-treated animals. This effect was specific for dopamine receptors and was transient as no significant modifications were observed when animals were treated for either 2 or 7 days. Administration of amantadine did not directly affect the animal behaviour. However, treated animals exhibited hypersensitive dopamine transmission since rats treated for 4 days showed exacerbated responses to a single apomorphine administration (enhanced locomotor activity and reduced stereotypy). Since the effects of amantadine administration differ from those usually observed with direct dopamine receptor agonists or other NMDA receptor antagonists, we suggest that multiple biochemical mechanisms contribute to the modulation of dopamine transmission by amantadine.
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Affiliation(s)
- Magali Peeters
- Laboratoire de Pharmacologie Expérimentale (FARL), Université Catholique de Louvain 54.10, Avenue Hippocrate 54, B-1200 Brussels, Belgium
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20
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Newman-Tancredi A, Cussac D, Brocco M, Rivet JM, Chaput C, Touzard M, Pasteau V, Millan MJ. Dopamine D2 receptor-mediated G-protein activation in rat striatum: functional autoradiography and influence of unilateral 6-hydroxydopamine lesions of the substantia nigra. Brain Res 2001; 920:41-54. [PMID: 11716810 DOI: 10.1016/s0006-8993(01)02927-4] [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: 11/30/2022]
Abstract
Unilateral 6-hydroxydopamine (6-OHDA) lesions of substantia nigra pars compacta (SNPC) neurons in rats induce behavioural hypersensitivity to dopaminergic agonists. However, the role of specific dopamine receptors is unclear, and potential alterations in their transduction mechanisms remain to be evaluated. The present study addressed these issues employing the dopaminergic agonist, quinelorane, which efficaciously stimulated G-protein activation (as assessed by [35S]GTPgammaS binding) at cloned hD2 (and hD3) receptors. At rat striatal membranes, dopamine stimulated [35S]GTPgammaS binding by 1.9-fold over basal, but its actions were only partially reversed by the selective D2/D3 receptor antagonist, raclopride, indicating the involvement of other receptor subtypes. In contrast, quinelorane-induced stimulation (48% of the effect of dopamine) was abolished by raclopride, and by the D2 receptor antagonist, L741,626. Further, novel antagonists selective for D3 and D4 receptors, S33084 and S18126, respectively, blocked the actions of quinelorane at concentrations corresponding to their affinities for D2 receptors. Quinelorane potently induced contralateral rotation in unilaterally 6-OHDA-lesioned rats, an effect abolished by raclopride and L741,626, but not by D3 and D4 receptor-selective doses of S33084 and S18126, respectively. In functional ([35S]GTPgammaS) autoradiography experiments, quinelorane stimulated G-protein activation in caudate putamen and, to a lesser extent, in nucleus accumbens and cingulate cortex of naive rats. In unilaterally SNPC-lesioned rats, quinelorane-induced G-protein activation in the caudate putamen on the non-lesioned side was similar to that seen in naive animals (approximately 50% stimulation), but significantly greater on the lesioned side (approximately 80%). This increase was both pharmacologically and regionally specific since it was reversed by raclopride, and was not observed in nucleus accumbens or cingulate cortex. In conclusion, the present data indicate that, in rat striatum, the actions of quinelorane are mediated primarily by D2 receptors, and suggest that behavioural hypersensitivity to this agonist, induced by unilateral SNPC lesions, is associated with an increase in D2, but not D3 or D4, receptor-mediated G-protein activation.
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Affiliation(s)
- A Newman-Tancredi
- Department of Psychopharmacology, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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21
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Panchalingam S, Undie AS. SKF83959 exhibits biochemical agonism by stimulating [(35)S]GTP gamma S binding and phosphoinositide hydrolysis in rat and monkey brain. Neuropharmacology 2001; 40:826-37. [PMID: 11369036 DOI: 10.1016/s0028-3908(01)00011-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SKF83959, a benzazepine with high affinity for aminergic receptors, elicits behaviors such as grooming and vacuous chewing that are characteristic of dopamine D(1)-like receptor stimulation in rodents. Unlike classical D(1) agonists, however, SKF83959 does not stimulate adenylyl cyclase. Knowing that some D(1)-like receptors are coupled to phospholipase C-mediated signaling cascades in the brain, the present study aimed to determine whether SKF83959 exhibits an agonistic action at the biochemical level and also whether this benzazepine can modulate phosphoinositide hydrolysis in a manner that would be consistent with the behavioral effects of the drug. Similar to dopamine and the selective D(1)-like agonist SKF38393, SKF83959 competitively displaced the receptor binding of [(3)H]dopamine in an agonist-like manner, significantly stimulated [(35)S]guanosine-5'-O-(3-thio)triphosphate binding, and potently enhanced phospholipase C-mediated phosphoinositide hydrolysis in rat and monkey brain tissues. SKF83959 was generally more potent than SKF38393, whereas SKF38393 consistently exhibited greater pharmacological efficacy. These findings may implicate a role for the phospholipase C signaling cascade in the agonistic behavioral and antiparkinsonian activity of SKF83959. Dopamine-sensitive phospholipase C signaling should probably be considered in subsequent formulations of mechanisms and models of dopaminergic function in the normal or diseased brain.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/analogs & derivatives
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Benzazepines/metabolism
- Brain/drug effects
- Brain/metabolism
- Cytidine Diphosphate Diglycerides/metabolism
- Dopamine/metabolism
- Dopamine Agonists/pharmacology
- Dose-Response Relationship, Drug
- Female
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Inositol Phosphates/metabolism
- Macaca mulatta
- Male
- Phosphatidylinositols/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/metabolism
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Affiliation(s)
- S Panchalingam
- Neuropharmacology Laboratory, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore MD 21201, USA
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22
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He L, Di Monte DA, Langston JW, Quik M. Autoradiographic analysis of dopamine receptor-stimulated [(35)S]GTPgammaS binding in rat striatum. Brain Res 2000; 885:133-6. [PMID: 11121540 DOI: 10.1016/s0006-8993(00)02981-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autoradiographic analysis of [(35)S]GTPgammaS binding was used to investigate functional activation of dopamine receptors in rat striatum. Dopamine-stimulated [(35)S]GTPgammaS binding was observed with a maximal increase of 38% over basal activity. A similar stimulatory response was obtained with the D(2) agonist quinpirole, but not SKF-238393, a D(1) agonist. The effect of dopamine was blocked by the D(2) antagonist raclopride, but was unaffected by SCH-23990, a D(1) antagonist. There appeared to be a differential distribution of dopamine-stimulated [(35)S]GTPgammaS binding, with the lowest activity obtained in the medial portion of the caudal striatum. These results demonstrate, using an autoradiographic approach, (i) that dopamine stimulated [(35)S]GTPgammaS binding in the rat striatum occurs through activation of D(2) receptors, and (ii) that the effects of dopamine activation vary in different areas of the rat striatum.
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Affiliation(s)
- L He
- The Parkinson's Institute, 1170 Morse Avenue, Sunnyvale, CA 94089, USA
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23
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Gilliland SL, Alper RH, Levant B. Pharmacology of quinpirole-stimulated [35S]GTPgammaS binding: discrepancy with receptor binding profile. Eur J Pharmacol 2000; 392:125-8. [PMID: 10762663 DOI: 10.1016/s0014-2999(00)00124-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Functional consequences of receptor stimulation by quinpirole, a dopamine D(2)-like receptor agonist, were assessed using agonist-stimulated [35S]GTPgammaS binding in rat striatal membranes. Dopamine receptor antagonists inhibited quinpirole-stimulated [35SCH 23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4, 5-tetrahydro-1H-3-benzazepine), consistent with a dopamine D(2)-like profile. In contrast, the monoamine oxidase inhibitors Ro 41-1049 (N-(2-aminoethyl)-5-(3-fluorophenyl)-4-thiazolecarboxemide), and (+)- and (-)-deprenyl, which inhibit [3H]quinpirole binding, had no effect on agonist-independent or quinpirole-stimulated [35S]GTPgammaS binding. Clorgyline inhibited [35S]GTPgammaS binding by a non-dopamine D(2) receptor-mediated mechanism. These findings demonstrate a notable discrepancy between the pharmacological profile of [3H]quinpirole binding and quinpirole-stimulated [35S]GTPgammaS binding.
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Affiliation(s)
- S L Gilliland
- Departments of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160-7147, USA
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24
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Geurts M, Hermans E, Maloteaux JM. Enhanced striatal dopamine D(2) receptor-induced [35S]GTPgammaS binding after haloperidol treatment. Eur J Pharmacol 1999; 382:119-27. [PMID: 10528146 DOI: 10.1016/s0014-2999(99)00569-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dopamine receptor-G protein coupling and dopamine D(2) receptor density were assessed in rats treated for 3 weeks with either haloperidol (2 mg/kg; i.p.) or vehicle. After 3 days of withdrawal, agonist-induced guanosine 5'-O-(gamma-[35S]thio)triphosphate ([35S]GTPgammaS) and [3H]spiperone binding were determined in striatal homogenates. Maximal [3H]spiperone binding was increased (24.8%, P<0.01) following haloperidol treatment. The efficacy of dopamine and the dopamine D(2) receptor agonist R(-)-10, 11-dihydroxy-N-n-propylnorapomorphine (NPA) to induce [35S]GTPgammaS binding were found to be increased by 24.1% (P<0.01) and 44.6% (P<0. 001), respectively. When measured in the presence of a saturating concentration of a dopamine D(2) receptor antagonist, the response to dopamine was not significantly affected by haloperidol treatment. In addition, the measurement of haloperidol-induced catalepsy confirmed that the efficient dopamine receptor blockade was followed by a progressive development of dopaminergic supersensitivity. Taken together, these results indicate that a functional pool of dopamine D(2) receptors is increased after prolonged haloperidol administration.
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Affiliation(s)
- M Geurts
- Laboratoire de pharmacologie, U.C.L. 54.10, Université catholique de Louvain, Avenue Hippocrate 54, B-1200, Brussels, Belgium
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25
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Geurts M, Hermans E, Cumps J, Maloteaux JM. Dopamine receptor-modulated [35S]GTPgammaS binding in striatum of 6-hydroxydopamine-lesioned rats. Brain Res 1999; 841:135-42. [PMID: 10546996 DOI: 10.1016/s0006-8993(99)01812-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of dopamine receptor-G protein coupling in the development of striatal dopamine receptor supersensitivity was studied in rats with a 6-hydroxydopamine (6-OHDA)-induced unilateral lesion of the nigrostriatal pathway. This coupling was assessed by the measurement of dopamine agonist-induced guanosine 5'-O-(gamma[35S]thio)triphosphate ([35S]GTP-gammaS) binding in striatal membranes, at different periods of time (1-5 weeks) following the microinjection of the neurotoxin. From the first to the fifth week following the lesion, basal and dopamine-stimulated [35S]GTPgammaS-specific binding were found to be enhanced in the denervated striata as compared to their control counterpart. D2 dopamine receptors were clearly demonstrated to be involved in this supersensitivity, as assessed by measuring N-propylnorapomorphine (NPA)-, quinpirole- and bromocriptine-induced [35S]GTPgammaS-specific binding. The involvement of D1 dopamine receptors was indirectly studied by the combination of dopamine with a saturating concentration of the selective and potent D2 antagonist domperidone. In these conditions, the remaining response to dopamine was also found to be significantly increased following the lesion. These results are consistent with the hypothesis that, in addition to D2 dopamine receptor upregulation, modulation of dopamine receptor-G protein interaction is involved in the hypersensitivity accompanying striatal dopamine depletion.
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Affiliation(s)
- M Geurts
- Laboratory of Pharmacology, FARL 5410, Université Catholique de Louvain, Brussels, Belgium
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