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Zarrindast MR, Mahboobi S, Sadat-Shirazi MS, Ahmadi S. Anxiolytic-like effect induced by the cannabinoid CB1 receptor agonist, arachydonilcyclopropylamide (ACPA), in the rat amygdala is mediated through the D1 and D2 dopaminergic systems. J Psychopharmacol 2011; 25:131-40. [PMID: 20685770 DOI: 10.1177/0269881110376688] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the present study the influence of the dopaminergic system(s) of the amygdala on the anxiolytic-like effect of the cannabinoid CB1 receptor agonist, arachydonilcyclopropylamide (ACPA), in male Wistar rats was investigated. An elevated plus-maze test of anxiety was used to assess anxiety-like behaviors. The results showed that bilateral intra-amygdala injections of ACPA (0.125, 1.25 and 5 ng/rat) and the mixed dopamine D1/D2 receptor agonist, apomorphine, at different doses (0.001, 0.01 and 0.1 µg/rat) increased percentage open arm time (%OAT) and percentage open arm entries (%OAE), indicating an anxiolytic-like effect for both of the drugs. In contrast, intra-amygdala administration of the dopamine D1 receptor antagonist SCH23390 (0.5 and 1 µg/rat) and the dopamine D2 receptor antagonist, sulpiride (2 and 3 µg/rat) decreased %OAT and %OAE, suggesting an anxiogenic-like effect for both of the drugs. Interestingly, pretreatment with a sub-effective dose of apomorphine (0.0005 µg/rat) increased, while SCH23390 (0.25 µg/rat) and sulpiride (1.5 µg/rat) decreased the anxiolytic-like effect of ACPA. It can be concluded that the dopaminergic system of the amygdala may be involved, at least partly, in the anxiolytic-like effects induced by ACPA in the rat amygdala.
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Affiliation(s)
- Mohammad Reza Zarrindast
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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102
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Thanos PK, Gopez V, Delis F, Michaelides M, Grandy DK, Wang GJ, Kunos G, Volkow ND. Upregulation of cannabinoid type 1 receptors in dopamine D2 receptor knockout mice is reversed by chronic forced ethanol consumption. Alcohol Clin Exp Res 2011; 35:19-27. [PMID: 20958329 PMCID: PMC3004984 DOI: 10.1111/j.1530-0277.2010.01318.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The anatomical proximity of the cannabinoid type 1 (CNR1/CB1R) and the dopamine D2 receptors (DRD2), their ability to form CB1R-DRD2 heteromers, their opposing roles in locomotion, and their involvement in ethanol's reinforcing and addictive properties prompted us to study the levels and distribution of CB1R after chronic ethanol intake, in the presence and absence of DRD2. METHODS We monitored the drinking patterns and locomotor activity of Drd2+/+ and Drd2-/- mice consuming either water or a 20% (v/v) ethanol solution (forced ethanol intake) for 6 months and used the selective CB1 receptor antagonist [³H]SR141716A to quantify CB1R levels in different brain regions with in vitro receptor autoradiography. RESULTS We found that the lack of DRD2 leads to a marked upregulation (approximately 2-fold increase) of CB1R in the cerebral cortex, the caudate-putamen, and the nucleus accumbens, which was reversed by chronic ethanol intake. CONCLUSIONS The results suggest that DRD2-mediated dopaminergic neurotransmission and chronic ethanol intake exert an inhibitory effect on cannabinoid receptor expression in cortical and striatal regions implicated in the reinforcing and addictive properties of ethanol.
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Affiliation(s)
- Panayotis K Thanos
- Department of Health and Human Services, Laboratory of Neuroimaging, NIAAA, NIH, Bethesda, Maryland, USA.
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103
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Albizu L, Moreno JL, González-Maeso J, Sealfon SC. Heteromerization of G protein-coupled receptors: relevance to neurological disorders and neurotherapeutics. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2010; 9:636-50. [PMID: 20632964 PMCID: PMC3066024 DOI: 10.2174/187152710793361586] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 03/30/2010] [Indexed: 11/22/2022]
Abstract
Because G protein-coupled receptors (GPCRs) are numerous, widely expressed and involved in major physiological responses, they represent a relevant therapeutic target for drug discovery, particularly regarding pharmacological treatments of neurological disorders. Among the biological phenomena regulating receptor function, GPCR heteromerization is an important emerging area of interest and investigation. There is increasing evidence showing that heteromerization contributes to the pharmacological heterogeneity of GPCRs by modulating receptor ontogeny, activation and recycling. Although in many cases the physiological relevance of receptor heteromerization has not been fully established, the unique pharmacological and functional properties of heteromers are likely to lead to new strategies in clinical medicine. This review describes the main GPCR heteromers and their implications for major neurological disorders such as Parkinson's disease, schizophrenia and addiction. A better understanding of molecular mechanisms underlying drug interactions related to the targeting of receptor heteromers could provide more specific and efficient therapeutic agents for the treatment of brain diseases.
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Affiliation(s)
- Laura Albizu
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA
- Center for Translational Systems Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - José L. Moreno
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Javier González-Maeso
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Stuart C. Sealfon
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA
- Center for Translational Systems Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
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104
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Gramage E, Rossi L, Granado N, Moratalla R, Herradón G. Genetic inactivation of pleiotrophin triggers amphetamine-induced cell loss in the substantia nigra and enhances amphetamine neurotoxicity in the striatum. Neuroscience 2010; 170:308-16. [PMID: 20620199 DOI: 10.1016/j.neuroscience.2010.06.078] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/26/2010] [Accepted: 06/29/2010] [Indexed: 01/04/2023]
Abstract
Pleiotrophin (PTN) is a neurotrophic factor with important effects in survival and differentiation of dopaminergic neurons that has been suggested to play important roles in drug of abuse-induced neurotoxicity. To test this hypothesis, we have studied the effects of amphetamine (10 mg/kg, four times, every 2 h) on the nigrostriatal pathway of PTN genetically deficient (PTN-/-) mice. We found that amphetamine causes a significantly enhanced loss of dopaminergic terminals in the striatum of PTN-/- mice compared to wild type (WT+/+) mice. In addition, we found a significant decrease ( approximately 20%) of tyrosine hydroxylase (TH)-positive neurons only in the substantia nigra of amphetamine-treated PTN-/- mice, whereas this area of WT+/+ animals remained unaffected after amphetamine treatment. This effect was accompanied by enhanced amphetamine-induced astrocytosis in the substantia nigra of PTN-/- mice. Interestingly, we found a significant decrease in the phosphorylation levels of p42 extracellular-signal regulated kinase (ERK2) in both saline- and amphetamine-treated PTN-/- mice, whereas phosphorylation of p44 ERK (ERK1) was almost abolished in the striatum of PTN-/- mice compared to WT+/+ mice, suggesting that basal deficiencies in the phosphorylation levels of ERK1/2 could underlie the higher vulnerability of PTN-/- mice to amphetamine-induced neurotoxic effects. The data suggest an important role of PTN in the protection of nigrostriatal pathways against amphetamine insult.
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Affiliation(s)
- E Gramage
- Lab. Pharmacology and Toxicology, University San Pablo CEU, 28668 Boadilla del Monte, Madrid, Spain
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105
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Barker JM, Torregrossa MM, Arnold AP, Taylor JR. Dissociation of genetic and hormonal influences on sex differences in alcoholism-related behaviors. J Neurosci 2010; 30:9140-4. [PMID: 20610747 PMCID: PMC2921163 DOI: 10.1523/jneurosci.0548-10.2010] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 05/06/2010] [Accepted: 05/26/2010] [Indexed: 11/21/2022] Open
Abstract
Differences between men and women in alcohol abuse prevalence have long been attributed to social and hormonal factors. It is, however, becoming apparent that sex differences in substance dependence are also influenced by genetic factors. Using a four core genotype mouse model that enables dissociation of chromosomal and gonadal sex, we show that habitual responding for alcohol reinforcement is mediated by sex chromosome complement independent of gonadal phenotype. After moderate instrumental training, chromosomal male (XY) mice became insensitive to outcome devaluation, indicating habitual responding. Chromosomal female (XX) mice remained sensitive to outcome devaluation, signifying goal-directed behavior. There was no effect of gonadal phenotype on habitual responding. Conversely, alcohol drinking was predicted by gonadal phenotype independent of sex chromosome complement. These results indicate that different alcoholism-related behaviors are determined independently by gonadal and chromosomal sex.
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Affiliation(s)
- Jacqueline M. Barker
- Department of Psychiatry, Yale University, Connecticut Mental Health Center, New Haven, Connecticut 06519, and
| | - Mary M. Torregrossa
- Department of Psychiatry, Yale University, Connecticut Mental Health Center, New Haven, Connecticut 06519, and
| | - Arthur P. Arnold
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California 90095
| | - Jane R. Taylor
- Department of Psychiatry, Yale University, Connecticut Mental Health Center, New Haven, Connecticut 06519, and
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106
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Ferré S, Lluís C, Justinova Z, Quiroz C, Orru M, Navarro G, Canela EI, Franco R, Goldberg SR. Adenosine-cannabinoid receptor interactions. Implications for striatal function. Br J Pharmacol 2010; 160:443-53. [PMID: 20590556 PMCID: PMC2931547 DOI: 10.1111/j.1476-5381.2010.00723.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 01/26/2010] [Accepted: 01/28/2010] [Indexed: 10/19/2022] Open
Abstract
Adenosine and endocannabinoids are very ubiquitous non-classical neurotransmitters that exert a modulatory role on the transmission of other more 'classical' neurotransmitters. In this review we will focus on their common role as modulators of dopamine and glutamate neurotransmission in the striatum, the main input structure of the basal ganglia. We will pay particular attention to the role of adenosine A(2A) receptors and cannabinoid CB(1) receptors. Experimental results suggest that presynaptic CB(1) receptors interacting with A(2A) receptors in cortico-striatal glutamatergic terminals that make synaptic contact with dynorphinergic medium-sized spiny neurons (MSNs) are involved in the motor-depressant and addictive effects of cannabinoids. On the other hand, postsynaptic CB(1) receptors interacting with A(2A) and D(2) receptors in the dendritic spines of enkephalinergic MSNs and postsynaptic CB(1) receptors in the dendritic spines of dynorphinergic MSN are probably involved in the cataleptogenic effects of cannabinoids. These receptor interactions most probably depend on the existence of a variety of heteromers of A(2A), CB(1) and D(2) receptors in different elements of striatal spine modules. Drugs selective for the different striatal A(2A) and CB(1) receptor heteromers could be used for the treatment of neuropsychiatric disorders and drug addiction and they could provide effective drugs with fewer side effects than currently used drugs.
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Affiliation(s)
- Sergi Ferré
- National Institute on Drug Abuse, IRP, NIH, DHHS, Baltimore, MD 21224, USA.
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107
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Zarrindast MR, Dorrani M, Lachinani R, Rezayof A. Blockade of dorsal hippocampal dopamine receptors inhibits state-dependent learning induced by cannabinoid receptor agonist in mice. Neurosci Res 2010; 67:25-32. [DOI: 10.1016/j.neures.2010.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/28/2010] [Accepted: 02/01/2010] [Indexed: 10/19/2022]
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108
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Jutras-Aswad D, Zang G, Bruneau J. Cannabis Use Correlates of Syringe Sharing among Injection Drug Users. Am J Addict 2010; 19:231-7. [DOI: 10.1111/j.1521-0391.2010.00031.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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109
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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: 8.0] [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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110
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Intra-accumbens rimonabant is rewarding but induces aversion to cocaine in cocaine-treated rats, as does in vivo accumbal cannabinoid CB1 receptor silencing: critical role for glutamate receptors. Neuroscience 2010; 167:205-15. [PMID: 20167255 DOI: 10.1016/j.neuroscience.2010.02.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 11/22/2022]
Abstract
Reinforcing effects mediated by accumbal CB(1) receptors (CB(1)R) are controversial, as well as their role in the rewarding effects of cocaine. Accumbal glutamate and glutamate receptors have been proposed to be involved in CB(1)R-mediated effects on cocaine reward. Rewarding effects of cocaine can be evaluated with the conditioned place preference or CPP test. Rimonabant, a cannabinoid CB(1)R ligand, lentiviruses aimed at silencing CB(1)R, and selective glutamatergic ligands are good tools for studying the function of accumbal CB(1) and glutamate receptors. The objectives of the present study were (i) to discern the CPP effects of in vivo gene silencing of accumbal CB(1) receptors by means of lentiviruses containing siRNAs; (ii) to discern the CPP effects of intra-accumbens infusions of the cannabinoid CB(1)R ligand rimonabant, and to evaluate whether effects are due to receptor blockade or inverse agonism; (iii) to discern the role of CB(1)R located within the nucleus accumbens shell in the rewarding effects of cocaine, by means of local infusions of rimonabant, and (iv) to discern the role of glutamate receptors (AMPAR, NMDAR, mGluR2/3) in rimonabant-induced effects on CPP in cocaine-treated rats. The findings revealed that in vivo silencing of accumbal CB(1) receptors with Lenti-CB(1)R-siRNAs induced place aversion to cocaine, but intra-accumbal rimonabant induced place preference in its own right, indicating that this compound seems to act as inverse agonist on the CPP. Glutamate receptors participate in rimonabant-mediated place preference because it was abolished after blocking AMPA glutamate receptors, but not NMDAR or mGluR2/3. Finally, in cocaine-treated rats, local rimonabant induced place aversion to the drug (not place preference), and this effect was mediated by glutamate neurotransmission because it was abolished after blockade of AMPA, NMDA or mGlu2/3 receptors, even though only the blockade of mGlu2/3 autoreceptors restored the emergence of place preference to cocaine.
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111
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Urigüen L, García-Fuster MJ, Callado LF, Morentin B, La Harpe R, Casadó V, Lluis C, Franco R, García-Sevilla JA, Meana JJ. Immunodensity and mRNA expression of A2A adenosine, D2 dopamine, and CB1 cannabinoid receptors in postmortem frontal cortex of subjects with schizophrenia: effect of antipsychotic treatment. Psychopharmacology (Berl) 2009; 206:313-24. [PMID: 19652957 DOI: 10.1007/s00213-009-1608-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2009] [Accepted: 07/01/2009] [Indexed: 11/28/2022]
Abstract
RATIONALE Dopamine D2 receptors are the main target of antipsychotic drugs. In the brain, D2 receptors coexpress with adenosine A2A and CB1 cannabinoid receptors, leading to functional interactions. OBJECTIVES The protein and messenger RNA (mRNA) contents of A2A, D2, and CB1 receptors were quantified in postmortem prefrontal cortex of subjects with schizophrenia. MATERIALS AND METHODS The study was performed in subjects suffering schizophrenia (n=31) who mainly died by suicide, matched with non-schizophrenia suicide victims (n=13) and non-suicide controls (n=33). The density of receptor proteins was evaluated by immunodetection techniques, and their relative mRNA expression was quantified by quantitative real-time polymerase chain reaction. RESULTS In schizophrenia, the densities of A2A (90+/-6%, n=24) and D2-like receptors (95+/-5%, n=22) did not differ from those in controls (100%). Antipsychotic treatment did not induce changes in the protein expression. In contrast, the immunodensity of CB1 receptors was significantly decreased (71+/-7%, n=11; p<0.05) in antipsychotic-treated subjects with schizophrenia but not in drug-free subjects (104+/-13%, n=11). The relative mRNA amounts encoding for A2A, D2, and CB1 receptors were similar in brains of drug-free, antipsychotic-treated subjects with schizophrenia and controls. CONCLUSIONS The findings suggest that antipsychotics induce down-regulation of CB1 receptors in brain. Since A2A, D2, and CB1 receptors coexpress on brain GABAergic neurons and reductions in markers of GABA neurotransmission have been identified in schizophrenia, a lower density of CB1 receptor induced by antipsychotics could represent an adaptative mechanism that reduces the endocannabinoid-mediated suppression of GABA release, contributing to the normalization of cognitive functions in the disorder.
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Affiliation(s)
- Leyre Urigüen
- Department of Pharmacology, University of the Basque Country, 48940, Leioa, Bizkaia, Spain
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112
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Granado N, Ares-Santos S, O'Shea E, Vicario-Abejón C, Colado MI, Moratalla R. Selective vulnerability in striosomes and in the nigrostriatal dopaminergic pathway after methamphetamine administration : early loss of TH in striosomes after methamphetamine. Neurotox Res 2009; 18:48-58. [PMID: 19760475 PMCID: PMC2875475 DOI: 10.1007/s12640-009-9106-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 07/30/2009] [Accepted: 08/21/2009] [Indexed: 12/26/2022]
Abstract
Methamphetamine (METH), a commonly abused psychostimulant, causes dopamine neurotoxicity in humans, rodents, and nonhuman primates. This study examined the selective neuroanatomical pattern of dopaminergic neurotoxicity induced by METH in the mouse striatum. We examined the effect of METH on tyrosine hydroxylase (TH) and dopamine transporter (DAT) immunoreactivity in the different compartments of the striatum and in the nucleus accumbens. The levels of dopamine and its metabolites, 3,4-dihidroxyphenylacetic acid and homovanillic acid, as well as serotonin (5-HT) and its metabolite, 5-hydroxyindolacetic acid, were also quantified in the striatum. Mice were given three injections of METH (4 mg/kg, i.p.) at 3 h intervals and sacrificed 7 days later. This repeated METH injection induced a hyperthermic response and a decrease in striatal concentrations of dopamine and its metabolites without affecting 5-HT concentrations. In addition, the drug caused a reduction in TH- and DAT-immunoreactivity when compared to saline-treated animals. Interestingly, there was a significantly greater loss of TH- and DAT-immunoreactivity in striosomes than in the matrix. The predominant loss of dopaminergic terminals in the striosomes occurred along the rostrocaudal axis of the striatum. In contrast, METH did not decrease TH- or DAT-immunoreactivity in the nucleus accumbens. These results provide the first evidence that compartments of the mouse striatum, striosomes and matrix, and mesolimbic and nigrostriatal pathways have different vulnerability to METH. This pattern is similar to that observed with other neurotoxins such as MPTP, the most widely used model of Parkinson’s disease, in early Huntington’s disease and hypoxic/ischemic injury, suggesting that these conditions might share mechanisms of neurotoxicity.
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Affiliation(s)
- Noelia Granado
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Dr. Arce 37, 28002, Madrid, Spain
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113
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O’Neill C, Evers-Donnelly A, Nicholson D, O’Boyle KM, O’Connor JJ. D2receptor-mediated inhibition of dopamine release in the rat striatumin vitrois modulated by CB1receptors: studies using fast cyclic voltammetry. J Neurochem 2009; 108:545-51. [DOI: 10.1111/j.1471-4159.2008.05782.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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114
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Morgese MG, Cassano T, Gaetani S, Macheda T, Laconca L, Dipasquale P, Ferraro L, Antonelli T, Cuomo V, Giuffrida A. Neurochemical changes in the striatum of dyskinetic rats after administration of the cannabinoid agonist WIN55,212-2. Neurochem Int 2009; 54:56-64. [PMID: 19010365 PMCID: PMC2657321 DOI: 10.1016/j.neuint.2008.10.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2008] [Accepted: 10/20/2008] [Indexed: 11/30/2022]
Abstract
Chronic use of levodopa, the most effective treatment for Parkinson's disease, causes abnormal involuntary movements named dyskinesias, which are linked to maladaptive changes in plasticity and disturbances of dopamine and glutamate neurotransmission in the basal ganglia. Dyskinesias can be modeled in rats with unilateral 6-hydroxydopamine lesions by repeated administration of low doses of levodopa (6 mg/kg, s.c.). Previous studies from our lab showed that sub-chronic treatment with the cannabinoid agonist WIN55,212-2 attenuates levodopa-induced dyskinesias at doses that do not interfere with physiological motor function. To investigate the neurochemical changes underlying WIN55,212-2 anti-dyskinetic effects, we used in vivo microdialysis to monitor extracellular dopamine and glutamate in the dorsal striatum of both the hemispheres of freely moving 6-hydroxydopamine-treated, SHAM-operated and intact rats receiving levodopa acutely or chronically (11 days), and studied how sub-chronic WIN55,212-2 (1 injection x 3 days, 20 min before levodopa) affected these neurochemical outputs. Our data indicate that: (1) the 6-hydroxydopamine lesion decreases dopamine turnover in the denervated striatum; (2) levodopa injection reduces extracellular glutamate in the side ipsilateral to the lesion of dyskinetic rats; (3) sub-chronic WIN55,212-2 prevents levodopa-induced glutamate volume transmission unbalances across the two hemispheres; and (4) levodopa-induced dyskinesias are inversely correlated with glutamate levels in the denervated striatum. These data indicate that the anti-dyskinetic properties of WIN55,212-2 are accompanied by changes of dopamine and glutamate outputs in the two brain hemispheres of 6-hydroxydopamine-treated rats.
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Affiliation(s)
- M G Morgese
- Department of Biomedical Sciences, University of Foggia, Italy
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115
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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 PMCID: PMC2635338 DOI: 10.1016/j.neuropharm.2008.06.076] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [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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