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Agnati LF, Guidolin D, Albertin G, Trivello E, Ciruela F, Genedani S, Tarakanov A, Fuxe K. An integrated view on the role of receptor mosaics at perisynaptic level: focus on adenosine A2A, dopamine D2, cannabinoid CB1, and metabotropic glutamate mGlu5receptors. J Recept Signal Transduct Res 2010; 30:355-69. [DOI: 10.3109/10799893.2010.487492] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Rossi S, De Chiara V, Musella A, Sacchetti L, Cantarella C, Castelli M, Cavasinni F, Motta C, Studer V, Bernardi G, Cravatt BF, Maccarrone M, Usiello A, Centonze D. Preservation of Striatal Cannabinoid CB1 Receptor Function Correlates with the Antianxiety Effects of Fatty Acid Amide Hydrolase Inhibition. Mol Pharmacol 2010; 78:260-8. [DOI: 10.1124/mol.110.064196] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Cannabinoid-dopamine interaction in the pathophysiology and treatment of CNS disorders. CNS Neurosci Ther 2010; 16:e72-91. [PMID: 20406253 DOI: 10.1111/j.1755-5949.2010.00144.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Endocannabinoids and their receptors, mainly the CB(1) receptor type, function as a retrograde signaling system in many synapses within the CNS, particularly in GABAergic and glutamatergic synapses. They also play a modulatory function on dopamine (DA) transmission, although CB(1) receptors do not appear to be located in dopaminergic terminals, at least in the major brain regions receiving dopaminergic innervation, e.g., the caudate-putamen and the nucleus accumbens/prefrontal cortex. Therefore, the effects of cannabinoids on DA transmission and DA-related behaviors are generally indirect and exerted through the modulation of GABA and glutamate inputs received by dopaminergic neurons. Recent evidence suggest, however, that certain eicosanoid-derived cannabinoids may directly activate TRPV(1) receptors, which have been found in some dopaminergic pathways, thus allowing a direct regulation of DA function. Through this direct mechanism or through indirect mechanisms involving GABA or glutamate neurons, cannabinoids may interact with DA transmission in the CNS and this has an important influence in various DA-related neurobiological processes (e.g., control of movement, motivation/reward) and, particularly, on different pathologies affecting these processes like basal ganglia disorders, schizophrenia, and drug addiction. The present review will address the current literature supporting these cannabinoid-DA interactions, with emphasis in aspects dealing with the neurochemical, physiological, and pharmacological/therapeutic bases of these interactions.
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Adenosine-dopamine interactions in the pathophysiology and treatment of CNS disorders. CNS Neurosci Ther 2010; 16:e18-42. [PMID: 20345970 DOI: 10.1111/j.1755-5949.2009.00126.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Adenosine-dopamine interactions in the central nervous system (CNS) have been studied for many years in view of their relevance for disorders of the CNS and their treatments. The discovery of adenosine and dopamine receptor containing receptor mosaics (RM, higher-order receptor heteromers) in the striatum opened up a new understanding of these interactions. Initial findings indicated the existence of A(2A)R-D(2)R heterodimers and A(1)R-D(1)R heterodimers in the striatum that were followed by indications for the existence of striatal A(2A)R-D(3)R and A(2A)R-D(4)R heterodimers. Of particular interest was the demonstration that antagonistic allosteric A(2A)-D(2) and A(1)-D(1) receptor-receptor interactions take place in striatal A(2A)R-D(2)R and A(1)R-D(1)R heteromers. As a consequence, additional characterization of these heterodimers led to new aspects on the pathophysiology of Parkinson's disease (PD), schizophrenia, drug addiction, and l-DOPA-induced dyskinesias relevant for their treatments. In fact, A(2A)R antagonists were introduced in the symptomatic treatment of PD in view of the discovery of the antagonistic A(2A)R-D(2)R interaction in the dorsal striatum that leads to reduced D(2)R recognition and G(i/o) coupling in striato-pallidal GABAergic neurons. In recent years, indications have been obtained that A(2A)R-D(2)R and A(1)R-D(1)R heteromers do not exist as heterodimers, rather as RM. In fact, A(2A)-CB(1)-D(2) RM and A(2A)-D(2)-mGlu(5) RM have been discovered using a sequential BRET-FRET technique and by using the BRET technique in combination with bimolecular fluorescence complementation. Thus, other pathogenic mechanisms beside the well-known alterations in the release and/or decoding of dopamine in the basal ganglia and limbic system are involved in PD, schizophrenia and drug addiction. In fact, alterations in the stoichiometry and/or topology of A(2A)-CB(1)-D(2) and A(2A)-D(2)-mGlu5 RM may play a role. Thus, the integrative receptor-receptor interactions in these RM give novel aspects on the pathophysiology and treatment strategies, based on combined treatments, for PD, schizophrenia, and drug addiction.
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Tebano MT, Martire A, Chiodi V, Pepponi R, Ferrante A, Domenici MR, Frank C, Chen JF, Ledent C, Popoli P. Adenosine A2Areceptors enable the synaptic effects of cannabinoid CB1receptors in the rodent striatum. J Neurochem 2009; 110:1921-30. [DOI: 10.1111/j.1471-4159.2009.06282.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Fuxe K, Marcellino D, Woods AS, Giuseppina L, Antonelli T, Ferraro L, Tanganelli S, Agnati LF. Integrated signaling in heterodimers and receptor mosaics of different types of GPCRs of the forebrain: relevance for schizophrenia. J Neural Transm (Vienna) 2009; 116:923-39. [PMID: 19156349 PMCID: PMC2953764 DOI: 10.1007/s00702-008-0174-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 12/11/2008] [Indexed: 11/26/2022]
Abstract
Receptor-receptor interactions within receptor heterodimers and receptor mosaics formed by different types of GPCRs represent an important integrative mechanism for signaling in brain networks at the level of the plasma membrane. The malfunction of special heterodimers and receptor mosaics in the ventral striatum containing D(2) receptors and 5-HT(2A) receptors in cortical networks may contribute to disturbances of key pathways involving ventral striato-pallidal GABA neurons and mediodorsal thalamic prefrontal glutamate neurons that may lead to the development of schizophrenia. The ventral striatum transmits emotional information to the cerebral cortex through a D(2) regulated accumbal-ventral pallidal-mediodorsal-prefrontal circuit which is of special interest to schizophrenia in view of the reduced number of glutamate mediodorsal-prefrontal projections associated with this disease. This circuit is especially vulnerable to D(2) receptor activity in the nucleus accumbens, since it produces a reduction in the prefrontal glutamate drive from the mediodorsal nucleus. The following D(2) receptor containing heterodimers/receptor mosaics are of special interest to schizophrenia: A(2A)-D(2), mGluR5-D(2), CB(1)-D(2), NTS(1)-D(2) and D(2)-D(3) and are discussed in this review. They may have a differential distribution pattern in the local circuits of the ventral striato-pallidal GABA pathway, predominantly located extrasynaptically. Specifically, trimeric receptor mosaics consisting of A(2A)-D(2)-mGluR5 and CB(1)-D(2)-A(2A) may also exist in these local circuits and are discussed. The integration of receptor signaling within assembled heterodimers/receptor mosaics is brought about by agonists and allosteric modulators. These cause the intramembrane receptor-receptor interactions, via allosteric mechanisms, to produce conformational changes that pass over the receptor interfaces. Exogenous and endogenous cooperativity is discussed as well as the role of the cortical mGluR2-5-HT(2A) heterodimer/receptor mosaic in schizophrenia (Gonzalez-Maeso et al. 2008). Receptor-receptor interactions within receptor heterodimer/receptor mosaics of different receptors in the ventral striatum and cerebral cortex give novel strategies for treatment of schizophrenia involving, e.g., monotherapy with either A(2A), mGluR5, CB(1) or NTS(1) agonists or combined therapies with some of these agonists combined with D(2)-like antagonists that specifically target the ventral striatum. In addition, a combined targeting of receptor mosaics in the ventral striatum and in the cerebral cortex should also be considered.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
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Rajput PS, Kharmate G, Somvanshi RK, Kumar U. Colocalization of dopamine receptor subtypes with dopamine and cAMP-regulated phosphoprotein (DARPP-32) in rat brain. Neurosci Res 2009; 65:53-63. [PMID: 19465068 DOI: 10.1016/j.neures.2009.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 04/30/2009] [Accepted: 05/14/2009] [Indexed: 10/20/2022]
Abstract
In the present study using indirect immunofluorescence immunohistochemistry, co-immunoprecipitation and western blot analysis we determined the colocalization of dopamine receptors 1-5 and dopamine and cAMP-regulated phosphoprotein (DARPP-32) in rat brain cortex and striatum. All five DR subtypes and DARPP-32 were expressed in rat brain cortex and striatum. DARPP-32 positive neurons displayed comparative colocalization with DR1-5. In cingulate cortex, the colocalization of DR subtypes was greatly different from frontal or temporal cortex. D1R is one of the most predominant subtypes which colocalized with DARPP-32 in cortex as well as striatum and followed by D2R, D3R, D4R and D5R. Amongst all DR subtypes D5R was coexpressed the least with DARPP-32 positive neurons. Consistent with immunohistochemical data, western blot analysis also reveals comparable distribution of DR subtypes and DARPP-32 in cortex and striatum. Colocalization studies were also supported by using co-immunoprecipitate assay displaying DARPP-32 expression in DR immunoprecipitate from tissue lysate prepared from cortex and striatum. Taken together our data support receptor specific association of DARPP-32 with DR subtypes that might shed new information in drugs of abuse and pathophysiology of neurodegenerative diseases as well as neuropsychiatric disorders such as schizophrenia.
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Affiliation(s)
- Padmesh S Rajput
- Faculty of Pharmaceutical Sciences, Division of Pharmacology and Toxicology, The University of British Columbia, Vancouver, BC, Canada
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58
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Abstract
The adenosine receptors (ARs) in the nervous system act as a kind of "go-between" to regulate the release of neurotransmitters (this includes all known neurotransmitters) and the action of neuromodulators (e.g., neuropeptides, neurotrophic factors). Receptor-receptor interactions and AR-transporter interplay occur as part of the adenosine's attempt to control synaptic transmission. A(2A)ARs are more abundant in the striatum and A(1)ARs in the hippocampus, but both receptors interfere with the efficiency and plasticity-regulated synaptic transmission in most brain areas. The omnipresence of adenosine and A(2A) and A(1) ARs in all nervous system cells (neurons and glia), together with the intensive release of adenosine following insults, makes adenosine a kind of "maestro" of the tripartite synapse in the homeostatic coordination of the brain function. Under physiological conditions, both A(2A) and A(1) ARs play an important role in sleep and arousal, cognition, memory and learning, whereas under pathological conditions (e.g., Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, stroke, epilepsy, drug addiction, pain, schizophrenia, depression), ARs operate a time/circumstance window where in some circumstances A(1)AR agonists may predominate as early neuroprotectors, and in other circumstances A(2A)AR antagonists may alter the outcomes of some of the pathological deficiencies. In some circumstances, and depending on the therapeutic window, the use of A(2A)AR agonists may be initially beneficial; however, at later time points, the use of A(2A)AR antagonists proved beneficial in several pathologies. Since selective ligands for A(1) and A(2A) ARs are now entering clinical trials, the time has come to determine the role of these receptors in neurological and psychiatric diseases and identify therapies that will alter the outcomes of these diseases, therefore providing a hopeful future for the patients who suffer from these diseases.
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Affiliation(s)
- Ana M Sebastião
- Institute of Pharmacology and Neurosciences, Institute of Molecular Medicine, University of Lisbon, 1649-028 Lisbon, Portugal.
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59
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Abstract
Although drugs of abuse have different chemical structures and interact with different protein targets, all appear to usurp common neuronal systems that regulate reward and motivation. Addiction is a complex disease that is thought to involve drug-induced changes in synaptic plasticity due to alterations in cell signaling, gene transcription, and protein synthesis. Recent evidence suggests that drugs of abuse interact with and change a common network of signaling pathways that include a subset of specific protein kinases. The best studied of these kinases are reviewed here and include extracellular signal-regulated kinase, cAMP-dependent protein kinase, cyclin-dependent protein kinase 5, protein kinase C, calcium/calmodulin-dependent protein kinase II, and Fyn tyrosine kinase. These kinases have been implicated in various aspects of drug addiction including acute drug effects, drug self-administration, withdrawal, reinforcement, sensitization, and tolerance. Identifying protein kinase substrates and signaling pathways that contribute to the addicted state may provide novel approaches for new pharmacotherapies to treat drug addiction.
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Affiliation(s)
- Anna M Lee
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California at San Francisco, Emeryville, CA 94608, USA
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60
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Herrera RA, Oved JH, Reiss CS. Disruption of IFN-gamma- mediated antiviral activity in neurons: the role of cannabinoids. Viral Immunol 2008; 21:141-52. [PMID: 18570588 DOI: 10.1089/vim.2007.0109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Interferon-gamma (IFN-gamma) has potent antiviral activity in neurons which is affected by the production of nitric oxide (NO). This study examines the interactions between cannabinoid receptor-1 (CB(1)), IFNgamma-induced pathways, and inhibition of vesicular stomatitis virus (VSV) replication in neuronal cells. CB(1) is abundantly expressed in neurons of the CNS and the NB41A3 neuroblastoma cell line. CB(1) activation of NB41A3 cells by the synthetic cannabinoid, WIN55,212-2, is associated with an inhibition of Ca(2+) mobilization, leading to diminished nitric oxide synthase (NOS)-1 activity and the production of NO, in vitro. This ultimately results in antagonism of IFN-gamma-mediated antiviral activity and enhanced viral replication. Therefore, activation of cells expressing CB(1) by endogenous (or exogenous) ligands may contribute to decreased inflammation and to increased viral replication in neurons and disease in the CNS.
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Abstract
The relationships between executive processes, associative learning and different aspects of real world memory functioning were explored in a sample of cannabis users and nonusers. Measures of executive component processes, associative learning, everyday memory, prospective memory, and cognitive failures were administered. Relative to nonusers, cannabis users were found to be impaired in several aspects of real world memory functioning. No other group differences were apparent. The absence of cannabis related deficits in those executive component processes and aspects of learning that are believed to support real world memory processes is surprising given that cannabis related deficits were obtained in real world memory. The present results are discussed within the context of neuroimaging evidence which suggests that cannabis users may exhibit different patterns of neural activation when performing executive tasks while not always exhibiting deficits on these tasks.
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Affiliation(s)
- J E Fisk
- Department of Psychology, University of Central Lancashire, UK.
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62
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Chronic psychoemotional stress impairs cannabinoid-receptor-mediated control of GABA transmission in the striatum. J Neurosci 2008; 28:7284-92. [PMID: 18632932 DOI: 10.1523/jneurosci.5346-07.2008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Exposure to stressful events has a myriad of consequences in animals and in humans, and triggers synaptic adaptations in many brain areas. Stress might also alter cannabinoid-receptor-mediated transmission in the brain, but no physiological study has addressed this issue so far. In the present study, we found that social defeat stress, induced in mice by exposure to aggression, altered cannabinoid CB(1)-receptor-mediated control of synaptic transmission in the striatum. In fact, the presynaptic inhibition of GABAergic IPSCs induced by the cannabinoid CB(1) receptor agonist HU210 [(6aR)-trans-3-(1,1-dimethylheptyl)-6a,7,10,10a-tetrahydro-1-hydroxy-6,6-dimethyl-6H-dibenzo[b,d]pyran-9-methanol] was reduced after a single stressful episode and fully abolished after 3 and 7 d of stress exposure. Repeated psychoemotional stress also impaired the sensitivity of GABA synapses to endocannabinoids mobilized by group I metabotropic glutamate receptor stimulation, whereas the cannabinoid CB(1)-mediated control of glutamate transmission was unaffected by repeated exposure to an aggressor. Corticosteroids released in response to the activation of the hypothalamic-pituitary-adrenal axis played a major role in the synaptic defects observed in stressed animals, because these alterations were fully prevented by pharmacological blockade of glucocorticoid receptors and were mimicked by corticosterone injections. The recovery of stress-induced synaptic defects was favored when stressed mice were given access to a running wheel or to sucrose consumption, which function as potent natural rewards. A similar rescuing effect was obtained by a single injection of cocaine, a psychostimulant with strong rewarding properties. Targeting cannabinoid CB(1) receptors or endocannabinoid metabolism might be a valuable option to treat stress-associated neuropsychiatric conditions.
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63
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Fuxe K, Marcellino D, Rivera A, Diaz-Cabiale Z, Filip M, Gago B, Roberts D, Langel U, Genedani S, Ferraro L, de la Calle A, Narvaez J, Tanganelli S, Woods A, Agnati L. Receptor–receptor interactions within receptor mosaics. Impact on neuropsychopharmacology. ACTA ACUST UNITED AC 2008; 58:415-52. [DOI: 10.1016/j.brainresrev.2007.11.007] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 11/26/2007] [Accepted: 11/29/2007] [Indexed: 01/01/2023]
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Ferré S, Goldberg SR, Lluis C, Franco R. Looking for the role of cannabinoid receptor heteromers in striatal function. Neuropharmacology 2008; 56 Suppl 1:226-34. [PMID: 18691604 DOI: 10.1016/j.neuropharm.2008.06.076] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 06/16/2008] [Accepted: 06/29/2008] [Indexed: 02/07/2023]
Abstract
The introduction of two concepts, "local module" and "receptor heteromer", facilitates the understanding of the role of interactions between different neurotransmitters in the brain. In artificial cell systems, cannabinoid CB(1) receptors form receptor heteromers with dopamine D2, adenosine A2A and mu opioid receptors. There is indirect but compelling evidence for the existence of the same CB1 receptor heteromers in striatal local modules centered in the dendritic spines of striatal GABAergic efferent neurons, particularly at a postsynaptic location. Their analysis provides new clues for the role of endocannabinoids in striatal function, which cannot only be considered as retrograde signals that inhibit neurotransmitter release. Recent studies using a new method to detect heteromerization of more than two proteins, which consists of sequential BRET-FRET (SRET) analysis, has demonstrated that CB1, D2 and A2A receptors can form heterotrimers in transfected cells. It is likely that functional CB1-A2A-D2 receptor heteromers can be found where they are highly co-expressed, in the dendritic spines of GABAergic enkephalinergic neurons. The functional properties of these multiple receptor heteromers and their role in striatal function need to be determined.
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Affiliation(s)
- Sergi Ferré
- National Institute on Drug Abuse, Intramural Research Program, Biomedical Research Center, National Institutes of Health, Department of Health and Human Services, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
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Higuera-Matas A, Soto-Montenegro ML, del Olmo N, Miguéns M, Torres I, Vaquero JJ, Sánchez J, García-Lecumberri C, Desco M, Ambrosio E. Augmented acquisition of cocaine self-administration and altered brain glucose metabolism in adult female but not male rats exposed to a cannabinoid agonist during adolescence. Neuropsychopharmacology 2008; 33:806-13. [PMID: 17551541 DOI: 10.1038/sj.npp.1301467] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Marijuana consumption during adolescence has been proposed to be a stepping-stone for adult cocaine addiction. However, experimental evidence for this hypothesis is missing. In this work we chronically injected male and female Wistar rats with either the cannabinoid agonist CP 55,940 (CP; 0.4 mg/kg) or its corresponding vehicle. Adult acquisition (seven 30 min daily sessions) and maintenance (fourteen 2 h daily sessions) of cocaine self-administration (1 mg/kg), food-reinforced operant learning under conditions of normal (ad libitum access to food), and high motivation (food-restriction schedule) were measured. Additionally, brain metabolic activity was analyzed by means of [(18)F]-fluorodeoxyglucose positron emission tomography. During the acquisition phase, female CP-treated rats showed a higher rate of cocaine self-administration as compared to vehicle-treated females and males; no differences were found between both male groups. This effect disappeared in the maintenance phase. Moreover, no differences among groups were evident in the food-reinforced operant task, pointing to the cocaine-specific nature of the effect seen in self-administration rather than a general change in reward processing. Basal brain metabolic activity also changed in CP-treated females when compared to their vehicle-treated counterparts with no differences being found in the males; more specifically we observed a hyper activation of the frontal cortex and a hypo activation of the amygdalo-entorhinal cortex. Our results suggest that a chronic exposure to cannabinoids during adolescence alters the susceptibility to acquire cocaine self-administration, in a sex-specific fashion. This increased susceptibility could be related to the changes in brain metabolic activity induced by cannabinoids during adolescence.
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Affiliation(s)
- Alejandro Higuera-Matas
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educacion a Distancia, Madrid, Spain
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Antagonistic cannabinoid CB1/dopamine D2 receptor interactions in striatal CB1/D2 heteromers. A combined neurochemical and behavioral analysis. Neuropharmacology 2008; 54:815-23. [PMID: 18262573 DOI: 10.1016/j.neuropharm.2007.12.011] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 12/19/2007] [Accepted: 12/19/2007] [Indexed: 11/20/2022]
Abstract
In vitro results show the ability of the CB(1) receptor agonist CP 55,940 to reduce the affinity of D(2) receptor agonist binding sites in both the dorsal and ventral striatum including the nucleus accumbens shell. This antagonistic modulation of D(2) receptor agonist affinity was found to remain and even be enhanced after G-protein activation by Gpp(NH)p. Using the FRET technique in living HEK-293T cells, the formation of CB(1)-D(2) receptor heteromers, independent of receptor occupancy, was demonstrated. These data thereby indicate that the antagonistic intramembrane CB(1)/D(2) receptor-receptor interactions may occur in CB(1)/D(2) formed heteromers. Antagonistic CB(1)/D(2) interactions were also discovered at the behavioral level through an analysis of quinpirole-induced locomotor hyperactivity in rats. The CB(1) receptor agonist CP 55,940 at a dose that did not change basal locomotion was able to block quinpirole-induced increases in locomotor activity. In addition, not only the CB(1) receptor antagonist rimonobant but also the specific A(2A) receptor antagonist MSX-3 blocked the inhibitory effect of CB(1) receptor agonist on D(2)-like receptor agonist-induced hyperlocomotion. Taken together, these results give evidence for the existence of antagonistic CB(1)/D(2) receptor-receptor interactions within CB(1)/D(2) heteromers in which A(2A) receptors may also participate.
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Ferré S, Diamond I, Goldberg SR, Yao L, Hourani SMO, Huang ZL, Urade Y, Kitchen I. Adenosine A2A receptors in ventral striatum, hypothalamus and nociceptive circuitry implications for drug addiction, sleep and pain. Prog Neurobiol 2007; 83:332-47. [PMID: 17532111 PMCID: PMC2141681 DOI: 10.1016/j.pneurobio.2007.04.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 03/15/2007] [Accepted: 04/05/2007] [Indexed: 11/22/2022]
Abstract
Adenosine A2A receptors localized in the dorsal striatum are considered as a new target for the development of antiparkinsonian drugs. Co-administration of A2A receptor antagonists has shown a significant improvement of the effects of l-DOPA. The present review emphasizes the possible application of A2A receptor antagonists in pathological conditions other than parkinsonism, including drug addiction, sleep disorders and pain. In addition to the dorsal striatum, the ventral striatum (nucleus accumbens) contains a high density of A2A receptors, which presynaptically and postsynaptically regulate glutamatergic transmission in the cortical glutamatergic projections to the nucleus accumbens. It is currently believed that molecular adaptations of the cortico-accumbens glutamatergic synapses are involved in compulsive drug seeking and relapse. Here we review recent experimental evidence suggesting that A2A antagonists could become new therapeutic agents for drug addiction. Morphological and functional studies have identified lower levels of A2A receptors in brain areas other than the striatum, such as the ventrolateral preoptic area of the hypothalamus, where adenosine plays an important role in sleep regulation. Although initially believed to be mostly dependent on A1 receptors, here we review recent studies that demonstrate that the somnogenic effects of adenosine are largely mediated by hypothalamic A2A receptors. A2A)receptor antagonists could therefore be considered as a possible treatment for narcolepsy and other sleep-related disorders. Finally, nociception is another adenosine-regulated neural function previously thought to mostly involve A1 receptors. Although there is some conflicting literature on the effects of agonists and antagonists, which may partly be due to the lack of selectivity of available drugs, the studies in A2A receptor knockout mice suggest that A2A receptor antagonists might have some therapeutic potential in pain states, in particular where high intensity stimuli are prevalent.
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Affiliation(s)
- S Ferré
- Preclinical Pharmacology Section, National Institute on Drug Abuse, Intramural Research Program, Department of Health and Human Services, Baltimore, MD 21224, USA.
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Reis HJ, Rosa DVF, Guimarães MM, Souza BR, Barros AGA, Pimenta FJ, Souza RP, Torres KCL, Romano-Silva MA. Is DARPP-32 a potential therapeutic target? Expert Opin Ther Targets 2007; 11:1649-61. [DOI: 10.1517/14728222.11.12.1649] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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69
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Carriba P, Ortiz O, Patkar K, Justinova Z, Stroik J, Themann A, Müller C, Woods AS, Hope BT, Ciruela F, Casadó V, Canela EI, Lluis C, Goldberg SR, Moratalla R, Franco R, Ferré S. Striatal adenosine A2A and cannabinoid CB1 receptors form functional heteromeric complexes that mediate the motor effects of cannabinoids. Neuropsychopharmacology 2007; 32:2249-59. [PMID: 17356572 DOI: 10.1038/sj.npp.1301375] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mechanism of action responsible for the motor depressant effects of cannabinoids, which operate through centrally expressed cannabinoid CB1 receptors, is still a matter of debate. In the present study, we report that CB1 and adenosine A2A receptors form heteromeric complexes in co-transfected HEK-293T cells and rat striatum, where they colocalize in fibrilar structures. In a human neuroblastoma cell line, CB1 receptor signaling was found to be completely dependent on A2A receptor activation. Accordingly, blockade of A2A receptors counteracted the motor depressant effects produced by the intrastriatal administration of a cannabinoid CB1 receptor agonist. These biochemical and behavioral findings demonstrate that the profound motor effects of cannabinoids depend on physical and functional interactions between striatal A2A and CB1 receptors.
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MESH Headings
- Adenosine A2 Receptor Agonists
- Analysis of Variance
- Animals
- Arachidonic Acids/pharmacology
- Behavior, Animal
- Cannabinoids/agonists
- Cannabinoids/antagonists & inhibitors
- Cannabinoids/pharmacology
- Cell Line, Transformed
- Corpus Striatum/drug effects
- Corpus Striatum/metabolism
- Cyclic AMP/metabolism
- Drug Interactions
- Humans
- Luminescent Proteins/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Motor Activity/drug effects
- Protein Binding/drug effects
- Rats
- Rats, Wistar
- Receptor, Adenosine A2A/deficiency
- Receptor, Adenosine A2A/physiology
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/deficiency
- Receptor, Cannabinoid, CB1/physiology
- Transfection
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Affiliation(s)
- Paulina Carriba
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
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70
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Chiang YC, Chen JC. The role of the cannabinoid type 1 receptor and down-stream cAMP/DARPP-32 signal in the nucleus accumbens of methamphetamine-sensitized rats. J Neurochem 2007; 103:2505-17. [PMID: 17953657 DOI: 10.1111/j.1471-4159.2007.04981.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Blockade of the cannabinoid type 1 (CB(1)) receptor could suppress methamphetamine self-administration; however, the cellular mechanism remains unclear. In this study, we intended to investigate the significance of brain CB(1) receptors on the development of behavioral sensitization to methamphetamine. Male Sprague-Dawley rats treated with chronic methamphetamine (4 mg/kg, i.p.) for either 7 or 14 days developed behavioral sensitization to methamphetamine (1 mg/kg) at withdrawal day 7. A progressive decrease in numbers of CB(1) receptor (both Bmax and mRNA) but increase in binding affinity (Kd) was noticed during withdrawal days 3 to 7. Microinjection of CB(1) antagonist [5-(4-bromophenyl)-1-(2,4-dichlorophenyl)-4-ethyl-N-(1-piperidinyl)-1H-pyrazole-3-carboxamide] into the nucleus accumbens (NAc) at withdrawal day 7, significantly suppressed the behavioral sensitization to methamphetamine. In NAc brain slices preparation, acute incubation with CB(1) agonist (1R,3R,4R)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl)cyclohexan-1-ol (CP 55940) dose-dependently enhanced cAMP accumulation in sensitized rats; no change was noticed in control groups. Consequently, treatment of CP 55940 induced a dose-dependent (10 nmol/L-10 micromol/L) phosphorylation on down-stream dopamine and cAMP-regulated phosphoprotein of Mr 32 000 (DARPP-32)/Thr34 in sensitized rats, while only 10 micromol/L CP 55940 was able to enhance the phosphoDARPP-32/T34 in control groups. Alternatively, both basal activity of calcineurin (PP-2B) and CP 55940-induced changes in the amount of PP-2B in the NAc were both decreased in sensitized rats, but not in controls. Overall, we demonstrated that brain CB(1) receptor and its down-stream cAMP/DARPP-32/T34/PP-2B signaling are profoundly altered in methamphetamine-sensitized animals.
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Affiliation(s)
- Yao-Chang Chiang
- Laboratory of Neuropharmacology, Department of Physiology and Pharmacology, Chang-Gung University and Molecular Imaging Center, Chang Gung Hospital, Kwei-Shan, Tao-Yuan, Taiwan, Republic of China
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71
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Borgkvist A, Marcellino D, Fuxe K, Greengard P, Fisone G. Regulation of DARPP-32 phosphorylation by Delta9-tetrahydrocannabinol. Neuropharmacology 2007; 54:31-5. [PMID: 17686497 DOI: 10.1016/j.neuropharm.2007.06.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 06/08/2007] [Accepted: 06/25/2007] [Indexed: 11/27/2022]
Abstract
CB1 receptor agonists increase the state of phosphorylation of the dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) at the cAMP-dependent protein kinase site, Thr 34. This effect, which occurs in the medium spiny neurons of the striatum, has been proposed to mediate the motor depressant action of cannabinoids. In this study, we have examined the effect produced by systemic administration of Delta(9)-tetrahydrocannabinol (THC), the major component of marihuana and hashish, on DARPP-32. We show that THC increases DARPP-32 phosphorylation at Thr 34 both in dorsal striatum and nucleus accumbens. Time-course and dose-response experiments indicate that DARPP-32 phosphorylation is maximal 30 min following administration of 10mg/kg of THC. The THC-mediated increase in DARPP-32 phosphorylation is reduced by administration of the CB1 receptor antagonist, SR141716A (3mg/kg). A similar attenuation of the effect of THC is also exerted by suppression of cAMP signaling achieved using the dopamine D1 receptor antagonist, SCH23390 (0.125 mg/kg), or the adenosine A2A receptor antagonist, KW6002 (3mg/kg). These results indicate that, in the striatum, THC promotes PKA-dependent phosphorylation of DARPP-32 in striatal medium spiny neurons expressing dopamine D1 and adenosine A2A receptors.
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Affiliation(s)
- Anders Borgkvist
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden
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72
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Schiffmann SN, Fisone G, Moresco R, Cunha RA, Ferré S. Adenosine A2A receptors and basal ganglia physiology. Prog Neurobiol 2007; 83:277-92. [PMID: 17646043 PMCID: PMC2148496 DOI: 10.1016/j.pneurobio.2007.05.001] [Citation(s) in RCA: 275] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2006] [Revised: 03/30/2007] [Accepted: 05/29/2007] [Indexed: 12/20/2022]
Abstract
Adenosine A2A receptors are highly enriched in the basal ganglia system. They are predominantly expressed in enkephalin-expressing GABAergic striatopallidal neurons and therefore are highly relevant to the function of the indirect efferent pathway of the basal ganglia system. In these GABAergic enkephalinergic neurons, the A2A receptor tightly interacts structurally and functionally with the dopamine D2 receptor. Both by forming receptor heteromers and by targeting common intracellular signaling cascades, A2A and D2 receptors exhibit reciprocal antagonistic interactions that are central to the function of the indirect pathway and hence to basal ganglia control of movement, motor learning, motivation and reward. Consequently, this A2A/D2 receptors antagonistic interaction is also central to basal ganglia dysfunction in Parkinson's disease. However, recent evidence demonstrates that, in addition to this post-synaptic site of action, striatal A2A receptors are also expressed and have physiological relevance on pre-synaptic glutamatergic terminals of the cortico-limbic-striatal and thalamo-striatal pathways, where they form heteromeric receptor complexes with adenosine A1 receptors. Therefore, A2A receptors play an important fine-tuning role, boosting the efficiency of glutamatergic information flow in the indirect pathway by exerting control, either pre- and/or post-synaptically, over other key modulators of glutamatergic synapses, including D2 receptors, group I metabotropic mGlu5 glutamate receptors and cannabinoid CB1 receptors, and by triggering the cAMP-protein kinase A signaling cascade.
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Affiliation(s)
- S N Schiffmann
- Laboratory of Neurophysiology, Université Libre de Bruxelles, Campus Erasme, 808 route de Lennik, CP601, 1070 Brussels, Belgium.
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73
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Corlett PR, Honey GD, Fletcher PC. From prediction error to psychosis: ketamine as a pharmacological model of delusions. J Psychopharmacol 2007; 21:238-52. [PMID: 17591652 DOI: 10.1177/0269881107077716] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent cognitive neuropsychiatric models of psychosis emphasize the role of attentional disturbances and inappropriate incentive learning in the development of delusions. These models highlight a pre-psychotic period in which the patient experiences perceptual and attentional disruptions. Irrelevant details and numerous associations between stimuli, thoughts and percepts are imbued with inappropriate significance and the attempt to rationalize and account for these bizarre experiences results in the formation of delusions. The present paper discusses delusion formation in terms of basic associative learning processes. Such processes are driven by prediction error signals. Prediction error refers to mismatches between an organism's expectation in a given environment and what actually happens and it is signalled by both dopaminergic and glutamatergic mechanisms. Disruption of these neurobiological systems may underlie delusion formation. We review similarities between acute psychosis and the psychotic state induced by the NMDA receptor antagonist drug ketamine, which impacts upon both dopaminergic and glutamatergic function. We conclude by suggesting that ketamine may provide an appropriate model to investigate the formative stages of symptom evolution in schizophrenia, and thereby provide a window into the earliest and otherwise inaccessible aspects of the disease process.
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Affiliation(s)
- P R Corlett
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, School of Clinical Medicine, Addenbrooke's Hospital, Hills Road, Cambridge, UK
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74
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Price DA, Owens WA, Gould GG, Frazer A, Roberts JL, Daws LC, Giuffrida A. CB1-independent inhibition of dopamine transporter activity by cannabinoids in mouse dorsal striatum. J Neurochem 2007; 101:389-96. [PMID: 17250681 DOI: 10.1111/j.1471-4159.2006.04383.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cannabinoid drugs are known to affect dopaminergic neurotransmission in the basal ganglia circuitry. In this study, we used in vitro and in vivo techniques to investigate whether cannabinoid agonists and antagonist could affect dopaminergic transmission in the striatum by acting at the dopamine transporter. Incubation of striatal synaptosomes with the cannabinoid agonists WIN55,212-2 or methanandamide decreased dopamine uptake (IC(50) = 2.0 micromol/L and 3.1 micromol/L, respectively). A similar inhibitory effect was observed after application of the inactive WIN55,212-2 isomer, S(-)WIN55,212-3. The CB(1) antagonist AM251 did not reverse WIN55,212-2 effect but rather mimicked it. WIN55,212-2 and AM251 partially displaced the binding of the cocaine analog [(3)H]WIN35,428, thus acting as dopamine transporter pseudo-substrates in the high micromolar range. High-speed chronoamperometry measurements showed that WIN55,212-2 (4 mg/kg, i.p.) caused significant release of endogenous dopamine via activation of CB(1) receptors, followed by a reduction of dopamine clearance. This reduction was CB(1)-independent, as it was mimicked by S(-)WIN55,212-3. Administration of AM251 (1 and 4 mg/kg, i.p.) increased the signal amplitude and reduced the clearance of dopamine pressure ejected into the striatum. These results indicate that both cannabinoid agonists and antagonists inhibit dopamine transporter activity via molecular targets other than CB(1) receptors.
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Affiliation(s)
- David A Price
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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75
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Harkany T, Guzmán M, Galve-Roperh I, Berghuis P, Devi LA, Mackie K. The emerging functions of endocannabinoid signaling during CNS development. Trends Pharmacol Sci 2007; 28:83-92. [PMID: 17222464 DOI: 10.1016/j.tips.2006.12.004] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 11/08/2006] [Accepted: 12/20/2006] [Indexed: 10/23/2022]
Abstract
In the postnatal brain, endocannabinoids acting as retrograde messengers regulate the function of many synapses. By contrast, the understanding of endocannabinoid functions that regulate fundamental developmental processes such as cell proliferation, migration, differentiation and survival during patterning of the CNS is just beginning to unfold. Increasing the knowledge of basic developmental and signaling principles that are controlled by endocannabinoids will provide important insights into the molecular mechanisms that establish functional neuronal circuits in the brain. Moreover, determining the molecular basis of permanent modifications to cellular structure and intercellular communication imposed by cannabis smoking during pregnancy will provide novel therapeutic targets for alleviating pathogenic changes in affected offspring. Here, we summarize recent findings regarding the ontogeny of the endocannabinoid system in neurons that sculpt the temporal and spatial diversity of cellular functions during CNS development.
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Affiliation(s)
- Tibor Harkany
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm SE-17177, Sweden.
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76
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77
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Hansen C, Greengard P, Nairn AC, Andersson T, Vogel WF. Phosphorylation of DARPP-32 regulates breast cancer cell migration downstream of the receptor tyrosine kinase DDR1. Exp Cell Res 2006; 312:4011-8. [PMID: 17027969 DOI: 10.1016/j.yexcr.2006.09.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 08/31/2006] [Accepted: 09/04/2006] [Indexed: 10/24/2022]
Abstract
Cell migration plays a central role in processes such as development, wound healing and cancer metastasis. Here we describe a novel interaction between DDR1, a receptor tyrosine kinase activated by collagen, and the phosphoprotein DARPP-32 in mammary epithelial cells. DARPP-32 expression was readily detected in non-transformed mammary cell lines, but was strongly reduced or even absent in breast tumor cell lines, such as MCF7. Transfection of MCF7 cells with DARPP-32 resulted in severely impaired cell migration, while DARPP-32 transfection into the DDR1-deficient breast cancer cell line MDA-MB-231 did not alter migration. Co-expression of both DDR1 and DARPP-32 in MDA-MB-231 cells inhibited migration, thereby supporting a critical role of the DDR1/DARPP-32 complex in motility. Mutational substitution of the phosphorylation sites Thr-34 or Thr-75 on DARPP-32 revealed that phosphorylation of Thr-34 is necessary for the ability of DARPP-32 to impair breast tumor cell migration. Thus, DARPP-32 signaling downstream of DDR1 is a potential new target for effective anti-metastatic breast cancer therapy.
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Affiliation(s)
- Christian Hansen
- Experimental Pathology from the Department of Laboratory Medicine, Lund University, University Hospital Malmö, 205 02 Malmö, Sweden
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78
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Pacher P, Bátkai S, Kunos G. The endocannabinoid system as an emerging target of pharmacotherapy. Pharmacol Rev 2006; 58:389-462. [PMID: 16968947 PMCID: PMC2241751 DOI: 10.1124/pr.58.3.2] [Citation(s) in RCA: 1458] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The recent identification of cannabinoid receptors and their endogenous lipid ligands has triggered an exponential growth of studies exploring the endocannabinoid system and its regulatory functions in health and disease. Such studies have been greatly facilitated by the introduction of selective cannabinoid receptor antagonists and inhibitors of endocannabinoid metabolism and transport, as well as mice deficient in cannabinoid receptors or the endocannabinoid-degrading enzyme fatty acid amidohydrolase. In the past decade, the endocannabinoid system has been implicated in a growing number of physiological functions, both in the central and peripheral nervous systems and in peripheral organs. More importantly, modulating the activity of the endocannabinoid system turned out to hold therapeutic promise in a wide range of disparate diseases and pathological conditions, ranging from mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis and spinal cord injury, to cancer, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity/metabolic syndrome, and osteoporosis, to name just a few. An impediment to the development of cannabinoid medications has been the socially unacceptable psychoactive properties of plant-derived or synthetic agonists, mediated by CB(1) receptors. However, this problem does not arise when the therapeutic aim is achieved by treatment with a CB(1) receptor antagonist, such as in obesity, and may also be absent when the action of endocannabinoids is enhanced indirectly through blocking their metabolism or transport. The use of selective CB(2) receptor agonists, which lack psychoactive properties, could represent another promising avenue for certain conditions. The abuse potential of plant-derived cannabinoids may also be limited through the use of preparations with controlled composition and the careful selection of dose and route of administration. The growing number of preclinical studies and clinical trials with compounds that modulate the endocannabinoid system will probably result in novel therapeutic approaches in a number of diseases for which current treatments do not fully address the patients' need. Here, we provide a comprehensive overview on the current state of knowledge of the endocannabinoid system as a target of pharmacotherapy.
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Affiliation(s)
- Pál Pacher
- Laboratory of Physiological Studies, National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Room 2S-24, Bethesda, MD 20892-9413, USA
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79
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Castañé A, Soria G, Ledent C, Maldonado R, Valverde O. Attenuation of nicotine-induced rewarding effects in A2A knockout mice. Neuropharmacology 2006; 51:631-40. [PMID: 16793068 DOI: 10.1016/j.neuropharm.2006.05.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 05/02/2006] [Accepted: 05/04/2006] [Indexed: 11/25/2022]
Abstract
The non-selective A2A antagonist caffeine has been reported to modify nicotine-induced locomotor and reinforcing effects. In the present study, we have investigated the specific role of A2A adenosine receptors in the behavioural responses induced by nicotine by using genetically modified mice lacking A2A adenosine receptors. Acute nicotine administration induced a similar decrease of locomotor activity in A2A knockout mice and wild-type littermates. Acute antinociceptive responses elicited by nicotine in the tail-immersion and hot-plate tests were unaffected in these mutant mice. The rewarding properties of nicotine were then investigated using the place-conditioning paradigm. Nicotine-induced conditioned place preference was suppressed in A2A knockout mice. Accordingly, in vivo microdialysis studies revealed that the extracellular levels of dopamine in the nucleus accumbens were not increased after nicotine administration in mutant mice. Wild-type and A2A knockout mice were trained in conditioned taste aversion procedure in which drinking a saccharin or saline solution was paired with nicotine or saline injections. A similar reduction in the intake of nicotine-paired solution in this paradigm was obtained in both genotypes. Finally, the administration of the nicotinic antagonist mecamylamine in nicotine-dependent mice precipitated a similar withdrawal syndrome in both genotypes. Together, the present results identify A2A adenosine receptors as an important factor that contributes to the rewarding properties of nicotine.
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Affiliation(s)
- Anna Castañé
- Laboratori de Neurofarmacologia, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Doctor Aiguader 80, 08003 Barcelona, Spain
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80
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Borgkvist A, Fisone G. Psychoactive drugs and regulation of the cAMP/PKA/DARPP-32 cascade in striatal medium spiny neurons. Neurosci Biobehav Rev 2006; 31:79-88. [PMID: 16730373 DOI: 10.1016/j.neubiorev.2006.03.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2006] [Revised: 03/13/2006] [Accepted: 03/13/2006] [Indexed: 11/28/2022]
Abstract
Changes in activity of the medium spiny neurons (MSNs) of dorsal and ventral striatum result in alterations of motor performance, ranging from rapid increases or decreases in locomotor activity, to long-term modifications of motor behaviours. In the dorsal striatum, MSNs can be distinguished based on the organization of their connectivity to substantia nigra pars reticulata (SNpr) and internal segment of the globus pallidus (GPi), which, in turn, control thalamocortical neurons. Approximately half of the MSNs project directly to SNpr and GPi, their activation leading to disinhibition of thalamocortical neurons and increased motor activity. The other subpopulation of MSNs connects to SNpr and GPi indirectly and when activated promotes inhibition of thalamocortical neurons, thereby reducing motor activity. The dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) is a modulator of the cAMP signalling pathway, highly expressed in MSNs. This review discusses the regulation of DARPP-32 exerted by psychoactive substances in specific populations of striatal projection neurons and its involvement in short- and long-term motor responses.
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Affiliation(s)
- Anders Borgkvist
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden
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81
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Myung JK, Lubec G. Use of Solution-IEF-Fractionation Leads to Separation of 2673 Mouse Brain Proteins Including 255 Hydrophobic Structures. J Proteome Res 2006; 5:1267-75. [PMID: 16674118 DOI: 10.1021/pr060015h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Analyzing complex protein mixtures on a single gel does not allow separation of many extracted proteins. Herein, we tried a prefractionation approach and mouse brain proteins were separated on a narrow pH range ZOOM-IEF Fractionator (MicroSol-IEF device) and run on two-dimensional gel electrophoresis. A total number of 2673 protein spots including 255 hydrophobic structures were successfully analyzed by mass spectrometry. This nonsophisticated approach to increase protein identification of a brain protein extract is a step forward in neurochemistry.
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Affiliation(s)
- Jae-Kyung Myung
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
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82
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Zhang Y, Svenningsson P, Picetti R, Schlussman SD, Nairn AC, Ho A, Greengard P, Kreek MJ. Cocaine self-administration in mice is inversely related to phosphorylation at Thr34 (protein kinase A site) and Ser130 (kinase CK1 site) of DARPP-32. J Neurosci 2006; 26:2645-51. [PMID: 16525043 PMCID: PMC6675152 DOI: 10.1523/jneurosci.3923-05.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The reinforcing effect of cocaine is associated with increases in dopamine in the striatum. The phosphoprotein DARPP-32 (dopamine- and cAMP-regulated phosphoprotein) has been shown to mediate the intracellular events after activation of dopamine receptors. DARPP-32 is phosphorylated at multiple sites by different protein kinases, but little is known about the functional role of these different sites. Cocaine self-administration and striatal levels of dopamine after acute "binge" cocaine administration were measured in separate lines of mice with alanine mutations introduced into DARPP-32 at either Thr34 (protein kinase A site, Thr34A), Thr75, (cyclin-dependent kinase 5 site, Thr75A), Ser97 (kinase CK2 site, Ser97A), or Ser130 (kinase CK1 site, Ser130A). Acquisition of stable cocaine self-administration required significantly more time in Thr34A-/- mice. Both Thr34A- and Ser130A-DARPP-32 mutant mice self-administered more cocaine than their respective wild-type controls. Also, cocaine-induced increases of dopamine in dorsal striatum were attenuated in the Thr34A- and Ser130A-DARPP-32 phosphomutant mice compared with wild-type mice. Notably, levels of P-Thr34- and P-Ser130-DARPP-32 were reduced after self-administration of cocaine in wild-type mice. Thus, phosphorylation states of Thr34- and Ser130-DARPP-32 play important roles in modulating the reinforcing effects of cocaine.
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Affiliation(s)
- Y Zhang
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, New York 10021, USA.
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