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Jin LE, Wang M, Yang ST, Yang Y, Galvin VC, Lightbourne TC, Ottenheimer D, Zhong Q, Stein J, Raja A, Paspalas CD, Arnsten AFT. mGluR2/3 mechanisms in primate dorsolateral prefrontal cortex: evidence for both presynaptic and postsynaptic actions. Mol Psychiatry 2017; 22:1615-1625. [PMID: 27502475 PMCID: PMC5298940 DOI: 10.1038/mp.2016.129] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/04/2016] [Accepted: 06/15/2016] [Indexed: 01/12/2023]
Abstract
Cognitive deficits in psychiatric and age-related disorders generally involve dysfunction of the dorsolateral prefrontal cortex (dlPFC), but there are few treatments for these debilitating symptoms. Group II metabotropic glutamate receptors (mGluR2/3), which couple to Gi/Go, have been a focus of therapeutics based on rodent research, where mGluR2/3 have been shown to reduce axonal glutamate release and increase glial glutamate uptake. However, this strategy has had mixed results in patients, and understanding mGluR2/3 mechanisms in primates will help guide therapeutic interventions. The current study examined mGluR2/3 localization and actions in the primate dlPFC layer III circuits underlying working memory, where the persistent firing of 'Delay cells' is mediated by N-methyl-d-aspartate receptors and weakened by cAMP-PKA-potassium channel signaling in dendritic spines. Immunoelectron microscopy identified postsynaptic mGluR2/3 in the spines, in addition to the traditional presynaptic and astrocytic locations. In vivo iontophoretic application of the mGluR2/3 agonists (2R, 4R)-APDC or LY379268 onto dlPFC Delay cells produced an inverted-U effect on working memory representation, with enhanced neuronal firing following low doses of mGluR2/3 agonists. The enhancing effects were reversed by an mGluR2/3 antagonist or by activating cAMP signaling, consistent with mGluR2/3 inhibiting postsynaptic cAMP signaling in spines. Systemic administration of these agonists to monkeys performing a working memory task also produced an inverted-U dose-response, where low doses improved performance but higher doses, similar to clinical trials, had mixed effects. Our data suggest that low doses of mGluR2/3 stimulation may have therapeutic effects through unexpected postsynaptic actions in dlPFC, strengthening synaptic connections and improving cognitive function.
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Affiliation(s)
- L E Jin
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - M Wang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - S-T Yang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Y Yang
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - V C Galvin
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - T C Lightbourne
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - D Ottenheimer
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Q Zhong
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - J Stein
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - A Raja
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - C D Paspalas
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA,Department of Neuroscience, Yale School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA. E-mail: or
| | - A F T Arnsten
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, CT, USA,Department of Neuroscience, Yale School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA. E-mail: or
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Muguruza C, Meana JJ, Callado LF. Group II Metabotropic Glutamate Receptors as Targets for Novel Antipsychotic Drugs. Front Pharmacol 2016; 7:130. [PMID: 27242534 PMCID: PMC4873505 DOI: 10.3389/fphar.2016.00130] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/05/2016] [Indexed: 11/13/2022] Open
Abstract
Schizophrenia is a chronic psychiatric disorder which substantially impairs patients' quality of life. Despite the extensive research in this field, the pathophysiology and etiology of schizophrenia remain unknown. Different neurotransmitter systems and functional networks have been found to be affected in the brain of patients with schizophrenia. In this context, postmortem brain studies as well as genetic assays have suggested alterations in Group II metabotropic glutamate receptors (mGluRs) in schizophrenia. Despite many years of drug research, several needs in the treatment of schizophrenia have not been addressed sufficiently. In fact, only 5-10% of patients with schizophrenia successfully achieve a full recovery after treatment. In recent years mGluRs have turned up as novel targets for the design of new antipsychotic medications for schizophrenia. Concretely, Group II mGluRs are of particular interest due to their regulatory role in neurotransmission modulating glutamatergic activity in brain synapses. Preclinical studies have demonstrated that orthosteric Group II mGluR agonists exhibit antipsychotic-like properties in animal models of schizophrenia. However, when these compounds have been tested in human clinical studies with schizophrenic patients results have been inconclusive. Nevertheless, it has been recently suggested that this apparent lack of efficacy in schizophrenic patients may be related to previous exposure to atypical antipsychotics. Moreover, the role of the functional heterocomplex formed by 5-HT2A and mGlu2 receptors in the clinical response to Group II mGluR agonists is currently under study.
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Affiliation(s)
- Carolina Muguruza
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
| | - J. Javier Meana
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
| | - Luis F. Callado
- Department of Pharmacology, University of the Basque Country, UPV/EHULeioa, Spain
- Centro de Investigación Biomédica en Red de Salud MentalMadrid, Spain
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Hisaoka-Nakashima K, Miyano K, Matsumoto C, Kajitani N, Abe H, Okada-Tsuchioka M, Yokoyama A, Uezono Y, Morioka N, Nakata Y, Takebayashi M. Tricyclic Antidepressant Amitriptyline-induced Glial Cell Line-derived Neurotrophic Factor Production Involves Pertussis Toxin-sensitive Gαi/o Activation in Astroglial Cells. J Biol Chem 2015; 290:13678-91. [PMID: 25869129 DOI: 10.1074/jbc.m114.622415] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Indexed: 11/06/2022] Open
Abstract
Further elaborating the mechanism of antidepressants, beyond modulation of monoaminergic neurotransmission, this study sought to elucidate the mechanism of amitriptyline-induced production of glial cell line-derived neurotrophic factor (GDNF) in astroglial cells. Previous studies demonstrated that an amitriptyline-evoked matrix metalloproteinase (MMP)/FGF receptor (FGFR)/FGFR substrate 2α (FRS2α)/ERK cascade is crucial for GDNF production, but how amitriptyline triggers this cascade remains unknown. MMP is activated by intracellular mediators such as G proteins, and this study sought to clarify the involvement of G protein signaling in amitriptyline-evoked GDNF production in rat C6 astroglial cells (C6 cells), primary cultured rat astrocytes, and normal human astrocytes. Amitriptyline-evoked GDNF mRNA expression and release were inhibited by pertussis toxin (PTX), a Gα(i/o) inhibitor, but not by NF449, a Gα(s) inhibitor, or YM-254890, a Gαq inhibitor. The activation of the GDNF production cascade (FGFR/FRS2α/ERK) was also inhibited by PTX. Deletion of Gα(ο1) and Gα(i3) by RNAi demonstrated that these G proteins play important roles in amitriptyline signaling. G protein activation was directly analyzed by electrical impedance-based biosensors (CellKey(TM) assay), using a label-free (without use of fluorescent proteins/probes or radioisotopes) and real time approach. Amitriptyline increased impedance, indicating Gα(i/o) activation that was suppressed by PTX treatment. The impedance evoked by amitriptyline was not affected by inhibitors of the GDNF production cascade. Furthermore, FGF2 treatment did not elicit any effect on impedance, indicating that amitriptyline targets PTX-sensitive Gα(i/o) upstream of the MMP/FGFR/FRS2α/ERK cascade. These results suggest novel targeting for the development of antidepressants.
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Affiliation(s)
- Kazue Hisaoka-Nakashima
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553,
| | - Kanako Miyano
- the Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, and
| | - Chie Matsumoto
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553
| | - Naoto Kajitani
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553
| | - Hiromi Abe
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, the Division of Psychiatry and Neuroscience, Institute for Clinical Research, and
| | - Mami Okada-Tsuchioka
- the Division of Psychiatry and Neuroscience, Institute for Clinical Research, and
| | - Akinobu Yokoyama
- the Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, and
| | - Yasuhito Uezono
- the Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, and
| | - Norimitsu Morioka
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553
| | - Yoshihiro Nakata
- From the Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553
| | - Minoru Takebayashi
- the Division of Psychiatry and Neuroscience, Institute for Clinical Research, and Department of Psychiatry, National Hospital Organization Kure Medical Center and Chugoku Cancer Center, 3-1 Aoyama, Kure 737-0023, Japan
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Fujáková M, Páleníček T, Brunovský M, Gorman I, Tylš F, Kubešová A, Řípová D, Krajča V, Horáček J. The effect of ((−)-2-oxa-4-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY379268), an mGlu2/3 receptor agonist, on EEG power spectra and coherence in ketamine model of psychosis. Pharmacol Biochem Behav 2014; 122:212-21. [DOI: 10.1016/j.pbb.2014.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 02/24/2014] [Accepted: 03/01/2014] [Indexed: 10/25/2022]
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Wyckhuys T, Wyffels L, Langlois X, Schmidt M, Stroobants S, Staelens S. The [18F]FDG μPET readout of a brain activation model to evaluate the metabotropic glutamate receptor 2 positive allosteric modulator JNJ-42153605. J Pharmacol Exp Ther 2014; 350:375-86. [PMID: 24898267 DOI: 10.1124/jpet.114.213959] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Using [(18)F]fluorodeoxyglucose μ-positron emission tomography ([(18)F]FDG μPET), we compared subanesthetic doses of memantine and ketamine on their potential to induce increases in brain activation. We also studied the reversal effect of the well-known metabotropic glutamate receptor (mGluR)-2/3 agonist LY404039 [(-)-(1R,4S,5S,6S)-4-amino-2-sulfonylbicyclo[3.1.0]hexane-4,6-dicarboxylic acid] and the novel mGluR2 positive allosteric modulator (PAM) JNJ-42153605 [3-cylcopropylmethyl-7-(4-phenylpiperidin-1-yl)-8-trifluoromethyl [1,2,4] triazolo[4,3-a]pyridine]. First, rats (n = 12) were subjected to LY404039 (10 mg/kg s.c.) or vehicle, 30 minutes prior to saline, ketamine (30 mg/kg i.p.), or memantine (20 mg/kg i.p.). Second, rats (n = 12) were subjected to 2.5 mg/kg or 10 mg/kg mGluR2 PAM JNJ-42153605 or vehicle (s.c.), 30 minutes prior to memantine (20 mg/kg i.p.) or saline. Fifteen minutes later, [(18)F]FDG was injected (37 MBq i.v.) followed by a μPET/computed tomography scan. The increase due to memantine is significant for all relevant brain areas, whereas for ketamine this is not the case. Standard uptake values (SUVs) of the LY404039 pretreated and memantine-challenged group display a full reversal. Pretreatment with JNJ-42153605 also dose-dependently decreases SUV with a full reversal as well (for 10 mg/kg). Moreover, specificity of JNJ-42153605 is reached at this dose. In conclusion, this μPET experiment clearly indicates that subanesthetic doses of memantine induce significant increases of [(18)F]FDG SUVs in discrete brain areas and that the novel mGluR2 PAM has the capacity to dose-dependently and specifically reverse memantine-induced brain activation.
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Affiliation(s)
- Tine Wyckhuys
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
| | - Xavier Langlois
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
| | - Mark Schmidt
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium (T.W., St.S.); Nuclear Medicine Department, University Hospital, Antwerp, Belgium (L.w., Si.S.); and Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium (X.L., M.S.)
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Methamphetamine and core temperature in the rat: ambient temperature, dose, and the effect of a D2 receptor blocker. Psychopharmacology (Berl) 2013; 228:551-61. [PMID: 23732837 DOI: 10.1007/s00213-013-3059-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 03/02/2013] [Indexed: 12/16/2022]
Abstract
RATIONALE Methamphetamine (METH) induces hyperthermia in warm and hypothermia in cool environments. Our first goal was to further study the role of ambient temperature in METH's effect on core temperature in rats. Previously, these effects were primarily demonstrated in high doses; we extended this investigation to the low-dose range (1 mg/kg METH). Our second goal was to identify the role of the D2 receptor in METH's effects in cool ambient temperatures. METHOD Rats received METH (saline, 1, 5, and 10 mg/kg), raclopride (saline, 0.3, 0.6, and 1.2 mg/kg), or a combination (all doses of raclopride combined with 10 mg/kg METH). Treatments occurred in ambient temperatures of 18, 24, or 30 °C. RESULTS AND CONCLUSIONS Consistent with prior research, 5 and 10 mg/kg METH caused hyperthermia or hypothermia in a dose- and ambient temperature-dependent manner (60 min after METH). In contrast, 1 mg/kg produced similar levels of hyperthermia at all ambient temperatures. These findings suggest that a threshold METH dose exists; below this dose, METH still changes core temperature, but CNS control over temperature regulation is left intact. In our experiments regarding D2 blockade, raclopride decreased METH-induced core temperature at 30 and 24 °C (60 min after METH), consistent with previous findings. We extended these findings by demonstrating that in a cool ambient temperature (18 °C), raclopride pretreatment also lowered the core temperature response to METH. Although the D2 receptor is known to mediate hypothermia, the combination of METH and D2 blockade suggests a complex mediation of the core temperature response, perhaps involving neurotransmitter interactions.
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The influence of ionotropic and metabotropic glutamate receptor ligands on anxiety-like effect of amphetamine withdrawal in rats. Prog Neuropsychopharmacol Biol Psychiatry 2013; 45:242-9. [PMID: 23623810 DOI: 10.1016/j.pnpbp.2013.04.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 01/22/2023]
Abstract
Chronic amphetamine use results in anxiety-like states after drug cessation. The aim of the study was to determine a role of ionotropic and metabotropic glutamate receptor ligands in amphetamine-evoked withdrawal anxiety in the elevated plus-maze test in rats. In our study memantine (8 and 12 mg/kg), a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist did not reduce amphetamine withdrawal anxiety. Acamprosate (NMDA and metabotropic glutamate 5 receptor (mGluR5) antagonist) at the dose 200 and 400mg/kg showed anxiolytic-like effect, thus increasing the percent of time spent in open arms and a number of open arm entries. mGluR5 selective antagonist, MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine hydrochloride) and mGluR2/3 agonist, LY354740 (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid), caused effects similar to acamprosate at doses 1.25-5mg/kg and 2.5-5mg/kg, respectively. None of the glutamate ligands influenced locomotor activity of rats when given to the saline-treated group. Taking into account the positive correlation between amphetamine withdrawal-induced anxiety and relapse to amphetamine taking, our results suggest that modulation of mGluRs may prevent relapse to amphetamine and might pose a new direction in amphetamine abuse therapy.
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Urbanek RA, Xiong H, Wu Y, Blackwell W, Steelman G, Rosamond J, Wesolowski SS, Campbell JB, Zhang M, Brockel B, Widzowski DV. Synthesis and SAR of aminothiazole fused benzazepines as selective dopamine D2 partial agonists. Bioorg Med Chem Lett 2012; 23:543-7. [PMID: 23237836 DOI: 10.1016/j.bmcl.2012.11.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 10/29/2012] [Accepted: 11/07/2012] [Indexed: 11/19/2022]
Abstract
Dopamine (D(2)) partial agonists (D2PAs) have been regarded as a potential treatment for schizophrenia patients with expected better side effect profiles than currently marketed antipsychotics. Herein we report the synthesis and SAR of a series of aminothiazole fused benzazepines as selective D(2) partial agonists. These compounds have good selectivity, CNS drug-like properties and tunable D(2) partial agonism. One of the key compounds, 8h, has good in vitro/in vivo ADME characteristics, and is active in a rat amphetamine-induced locomotor activity model.
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Affiliation(s)
- Rebecca A Urbanek
- CNS Discovery, AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, DE, USA
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Seeman P. Comment on: "Effects of a novel mGlu(2/3) receptor agonist prodrug, LY2140023 monohydrate, on central monoamine turnover as determined in human and rat cerebrospinal fluid" (Lowe S, Dean R, Ackermann B, Jackson K, Natanegara F, Anderson S, Eckstein J, Yuen E, Ayan-Oshodi M, Ho M, McKinzie D, Perry K, Svensson K, Psychopharmacology, 2012). Psychopharmacology (Berl) 2012; 221:355-6; author reply 357-8. [PMID: 22411429 DOI: 10.1007/s00213-012-2687-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 03/01/2012] [Indexed: 11/25/2022]
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10
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Cannady R, Grondin JJM, Fisher KR, Hodge CW, Besheer J. Activation of group II metabotropic glutamate receptors inhibits the discriminative stimulus effects of alcohol via selective activity within the amygdala. Neuropsychopharmacology 2011; 36:2328-38. [PMID: 21734651 PMCID: PMC3176569 DOI: 10.1038/npp.2011.121] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate receptor subtypes (mGlu2/3) regulate a variety of alcohol-associated behaviors, including alcohol reinforcement, and relapse-like behavior. To date, the role of mGlu2/3 receptors in modulating the discriminative stimulus effects of alcohol has not been examined. Given that the discriminative stimulus effects of drugs are determinants of abuse liability and can influence drug seeking, we examined the contributions of mGlu2/3 receptors in modulating the discriminative stimulus effects of alcohol. In male Long-Evans rats trained to discriminate between alcohol (1 g/kg, IG) and water, the mGlu2/3 agonist LY379268 (0.3-10 mg/kg) did not produce alcohol-like stimulus effects. However, pretreatment with LY379268 (1 and 3 mg/kg; in combination with alcohol) inhibited the stimulus effects of alcohol (1 g/kg). Systemic LY379268 (3 mg/kg, i.p.) was associated with increases in neuronal activity within the amygdala, but not the nucleus accumbens, as assessed by c-Fos immunoreactivity. Intra-amygdala activation of mGlu2/3 receptors by LY379268 (6 μg) inhibited the discriminative stimulus effects of alcohol, without altering response rate. In contrast, intra-accumbens LY379268 (3 μg) profoundly reduced response rate; however, at lower LY379268 doses (0.3, 1 μg), the discriminative stimulus effects of alcohol and response rate were not altered. These data suggest that amygdala mGlu2/3 receptors have a functional role in modulating the discriminative stimulus properties of alcohol and demonstrate differential motor sensitivity to activation of mGlu2/3 receptors in the amygdala and the accumbens. Understanding the neuronal mechanisms that underlie the discriminative stimulus effects of alcohol may prove to be important for future development of pharmacotherapies for treating alcoholism.
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Affiliation(s)
- Reginald Cannady
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Julie JM Grondin
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kristen R Fisher
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Clyde W Hodge
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Thurston-Bowles Building; CB #7178, Chapel Hill, NC 27599, USA. Tel: +1 919 843 4389; Fax: +1 919 966 5679; E-mail:
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