1
|
Kahvandi N, Ebrahimi Z, Sharifi M, Karimi SA, Shahidi S, Salehi I, Haddadi R, Sarihi A. S-3,4-DCPG, a potent orthosteric agonist for the mGlu8 receptor, facilitates extinction and inhibits the reinstatement of morphine-induced conditioned place preference in male rats. Pharmacol Biochem Behav 2024; 240:173772. [PMID: 38653345 DOI: 10.1016/j.pbb.2024.173772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 04/13/2024] [Accepted: 04/17/2024] [Indexed: 04/25/2024]
Abstract
The limbic system, particularly the NAc, shows a high concentration of metabotropic glutamate receptors (mGluRs). Recent evidence suggests the significant involvement of mGluRs in mental disorders, including substance abuse and addiction. The objective of this study was to examine the involvement of mGlu8 receptors in the NAc in the mechanisms underlying the extinction and reinstatement of conditioned place preference (CPP) induced by morphine. Male Wistar rats underwent surgical implantation of bilateral cannulas in the NAc and were assessed in a CPP protocol. In study 1 at the same time as the extinction phase, the rats were given varying doses of S-3,4-DCPG (0.03, 0.3, and 3 μg/0.5 μl). In study 2, rats that had undergone CPP extinction were given S-3,4-DCPG (0.03, 0.3, and 3 μg/0.5 μl) five minutes prior to receiving a subthreshold dose of morphine (1 mg/kg) in order to reactivate the previously extinguished morphine response. The findings demonstrated that administering S-3,4-DCPG directly into the accumbens nucleus resulted in a decrease in the duration of the CPP extinction phase. Moreover, dose-dependent administration of S-3,4-DCPG into the NAc inhibited CPP reinstatement. The observations imply that microinjection of S-3,4-DCPG as a potent orthosteric agonist with high selectivity for the mGlu8 receptor into the NAc promotes the process of extinction while concurrently exerting inhibitory effects on the reinstatement of morphine-induced CPP. This effect may be associated with the modulation of glutamate engagement within the NAc and the plasticity of reward pathways at the synaptic level.
Collapse
Affiliation(s)
- Nazanin Kahvandi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Physiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Zahra Ebrahimi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Physiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Maryam Sharifi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Seyed Asaad Karimi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Neuroscience, School of Sciences and Advanced Technology in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Siamak Shahidi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Neuroscience, School of Sciences and Advanced Technology in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Iraj Salehi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Neuroscience, School of Sciences and Advanced Technology in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Rasool Haddadi
- Department of Pharmacology and Toxicology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Abdolrahman Sarihi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; Department of Neuroscience, School of Sciences and Advanced Technology in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
| |
Collapse
|
2
|
Kallupi M, Ciccocioppo R. Cue-induced reinstatement of seeking behavior in male rats is independent from the rewarding value of the primary reinforcer: Effect of mGluR5 blockade. Neuropharmacology 2023; 240:109694. [PMID: 37659439 PMCID: PMC11094430 DOI: 10.1016/j.neuropharm.2023.109694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/04/2023]
Abstract
Environmental conditioning factors have a profound impact on alcohol-seeking behavior and the maintenance of alcohol use in individuals with alcohol dependence. Cues associated with alcohol, depending on the perceived value of the primary reinforcer, gain salience and can trigger relapse. This study investigates the correlation between the reward magnitude of the primary reinforcer and the reinstatement evoked by cues predictive of their availability in male rats. Rat self-administration procedures were used to test reinstatement, with reinforcers consisting of 10% alcohol, 10% sucrose, or 2% sodium chloride (NaCl) experienced under need-state conditions. The effect of MTEP ([(2-methyl-1,3-thiazol-4-yl) ethynyl] pyridine), a selective metabotropic glutamate receptor 5 (mGluR5) antagonist, on motivation and reinstatement behaviors was also evaluated. RESULTS: demonstrate that under Fixed Ratio 1 (FR1) schedule, the three reinforcers maintain operant responding with the following order of magnitude 10% sucrose >2% NaCl >10% alcohol > water. Under a progressive ratio (PR) schedule of reinforcement, rats exhibit a significantly higher breakpoint for 2% NaCl (under Na-depletion), followed by 10% sucrose and 10% alcohol. After extinction, a significant reinstatement is observed with the magnitude order of 10% sucrose >10% alcohol >2% NaCl. However, only re-exposure to alcohol-paired cues induced significant reinstatement of alcohol-seeking after 4 and 8 months. Treatment with MTEP significantly reduces reinstatement of responding across all reinforcers, with the strongest effect observed on alcohol-seeking. These findings suggest that mGluR5 plays a general role in controlling cue-reactivity, but the effect is prominent in the case of alcohol compared to natural rewards. In conclusion, the results demonstrate a remarkable dissociation between the rewarding magnitude of the primary reinforcer and its ability to trigger relapse upon presentation of a cue previously associated with it. Importantly, alcohol, despite having lower intrinsic motivational value compared to a natural reward (sucrose) or a consummatory stimulus experienced under need state conditions (NaCl), can elicit more robust and longer-term reinstatement of seeking responses. Finally, our data demonstrate a significant involvement of the mGluR5 system in the regulation of seeking behavior.
Collapse
Affiliation(s)
- Marsida Kallupi
- Department of Psychiatry, University of California, San Diego, USA.
| | - Roberto Ciccocioppo
- School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, Italy
| |
Collapse
|
3
|
Murray CH, Christian DT, Milovanovic M, Loweth JA, Hwang EK, Caccamise AJ, Funke JR, Wolf ME. mGlu5 function in the nucleus accumbens core during the incubation of methamphetamine craving. Neuropharmacology 2021; 186:108452. [PMID: 33444640 DOI: 10.1016/j.neuropharm.2021.108452] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 01/02/2021] [Accepted: 01/06/2021] [Indexed: 12/11/2022]
Abstract
Many studies have demonstrated that negative allosteric modulators (NAM) of metabotropic glutamate receptor 5 (mGlu5) reduce cocaine and methamphetamine seeking in extinction-reinstatement animal models of addiction. Less is known about effects of mGlu5 NAMs in abstinence models, particularly for methamphetamine. We used the incubation of drug craving model, in which cue-induced craving progressively intensifies after withdrawal from drug self-administration, to conduct the first studies of the following aspects of mGlu5 function in the rat nucleus accumbens (NAc) core during abstinence from methamphetamine self-administration: 1) functionality of the major form of synaptic depression in NAc medium spiny neurons, which is induced postsynaptically via mGlu5 and expressed presynaptically via cannabinoid type 1 receptors (CB1Rs), 2) mGlu5 surface expression and physical associations between mGlu5, Homer proteins, and diacylglycerol lipase-α, and 3) the effect of systemic and intra-NAc core administration of the mGlu5 NAM 3-((2-methyl-4-)ethynyl)pyridine (MTEP) on expression of incubated methamphetamine craving. We found that mGlu5/CB1R-dependent synaptic depression was lost during the rising phase of methamphetamine incubation but then recovered, in contrast to its persistent impairment during the plateau phase of incubation of cocaine craving. Furthermore, whereas the cocaine-induced impairment was accompanied by reduced mGlu5 levels and mGlu5-Homer associations, this was not the case for methamphetamine. Systemic MTEP reduced incubated methamphetamine seeking, but also reduced inactive hole nose-pokes and locomotion, while intra-NAc core MTEP had no significant effects. These findings provide the first insight into the role of mGlu5 in the incubation of methamphetamine craving and reveal differences from incubation of cocaine craving.
Collapse
Affiliation(s)
- Conor H Murray
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA; Department of Behavioral Neuroscience, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
| | - Daniel T Christian
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| | - Mike Milovanovic
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| | - Jessica A Loweth
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| | - Eun-Kyung Hwang
- Department of Behavioral Neuroscience, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
| | - Aaron J Caccamise
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
| | - Jonathan R Funke
- Department of Behavioral Neuroscience, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
| | - Marina E Wolf
- Department of Neuroscience, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA; Department of Behavioral Neuroscience, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
| |
Collapse
|
4
|
Alcohol. Alcohol 2021. [DOI: 10.1016/b978-0-12-816793-9.00001-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
5
|
Gregory KJ, Goudet C. International Union of Basic and Clinical Pharmacology. CXI. Pharmacology, Signaling, and Physiology of Metabotropic Glutamate Receptors. Pharmacol Rev 2020; 73:521-569. [PMID: 33361406 DOI: 10.1124/pr.119.019133] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors respond to glutamate, the major excitatory neurotransmitter in the mammalian brain, mediating a modulatory role that is critical for higher-order brain functions such as learning and memory. Since the first mGlu receptor was cloned in 1992, eight subtypes have been identified along with many isoforms and splice variants. The mGlu receptors are transmembrane-spanning proteins belonging to the class C G protein-coupled receptor family and represent attractive targets for a multitude of central nervous system disorders. Concerted drug discovery efforts over the past three decades have yielded a wealth of pharmacological tools including subtype-selective agents that competitively block or mimic the actions of glutamate or act allosterically via distinct sites to enhance or inhibit receptor activity. Herein, we review the physiologic and pathophysiological roles for individual mGlu receptor subtypes including the pleiotropic nature of intracellular signal transduction arising from each. We provide a comprehensive analysis of the in vitro and in vivo pharmacological properties of prototypical and commercially available orthosteric agonists and antagonists as well as allosteric modulators, including ligands that have entered clinical trials. Finally, we highlight emerging areas of research that hold promise to facilitate rational design of highly selective mGlu receptor-targeting therapeutics in the future. SIGNIFICANCE STATEMENT: The metabotropic glutamate receptors are attractive therapeutic targets for a range of psychiatric and neurological disorders. Over the past three decades, intense discovery efforts have yielded diverse pharmacological tools acting either competitively or allosterically, which have enabled dissection of fundamental biological process modulated by metabotropic glutamate receptors and established proof of concept for many therapeutic indications. We review metabotropic glutamate receptor molecular pharmacology and highlight emerging areas that are offering new avenues to selectively modulate neurotransmission.
Collapse
Affiliation(s)
- Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
| | - Cyril Goudet
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
| |
Collapse
|
6
|
The infralimbic cortex and mGlu5 mediate the effects of chronic intermittent ethanol exposure on fear learning and memory. Psychopharmacology (Berl) 2020; 237:3417-3433. [PMID: 32767063 PMCID: PMC7572878 DOI: 10.1007/s00213-020-05622-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/27/2020] [Indexed: 01/19/2023]
Abstract
RATIONALE AND OBJECTIVES Alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) often occur comorbidly. While the incidence of these disorders is increasing, there is little investigation into the interacting neural mechanisms between these disorders. These studies aim to identify cognitive deficits that occur as a consequence of fear and ethanol exposure, implement a novel pharmaceutical intervention, and determine relevant underlying neurocircuitry. Additionally, due to clinical sex differences in PTSD prevalence and alcohol abuse, these studies examine the nature of this relationship in rodent models. METHODS Animals were exposed to a model of PTSD+AUD using auditory fear conditioning followed by chronic intermittent ethanol exposure (CIE). Then, rats received extinction training consisting of multiple conditioned stimulus presentations in absence of the shock. Extinction recall and context-induced freezing were measured in subsequent tests. CDPPB, a metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulator, was used to treat these deficits, and region-specific effects were determined using microinjections. RESULTS These studies determined that CIE exposure led to deficits in fear extinction learning and heightened context-induced freezing while sex differences emerged in fear conditioning and extinction cue recall tests. Furthermore, using CDPPB, these studies found that enhancement of infralimbic (IfL) mGlu5 activity was able to recover CIE-induced deficits in both males and females. CONCLUSIONS These studies show that CIE induces deficits in fear-related behaviors and that enhancement of IfL glutamatergic activity can facilitate learning during extinction. Additionally, we identify novel pharmacological targets for the treatment of individuals who suffer from PTSD and AUD.
Collapse
|
7
|
Johnson KA, Lovinger DM. Allosteric modulation of metabotropic glutamate receptors in alcohol use disorder: Insights from preclinical investigations. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2020; 88:193-232. [PMID: 32416868 DOI: 10.1016/bs.apha.2020.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are family C G protein-coupled receptors (GPCRs) that modulate neuronal excitability and synaptic transmission throughout the nervous system. Owing to recent advances in development of subtype-selective allosteric modulators of mGlu receptors, individual members of the mGlu receptor family have been proposed as targets for treating a variety of neurological and psychiatric disorders, including substance use disorders. In this chapter, we highlight preclinical evidence that allosteric modulators of mGlu receptors could be useful for reducing alcohol consumption and preventing relapse in alcohol use disorder (AUD). We begin with an overview of the preclinical models that are used to study mGlu receptor involvement in alcohol-related behaviors. Alcohol exposure causes adaptations in both expression and function of various mGlu receptor subtypes, and pharmacotherapies aimed at reversing these adaptations have the potential to reduce alcohol consumption and seeking. Positive allosteric modulators (PAMs) of mGlu2 and negative allosteric modulators of mGlu5 show particular promise for reducing alcohol intake and/or preventing relapse. Finally, this chapter discusses important considerations for translating preclinical findings toward the development of clinically useful drugs, including the potential for PAMs to avoid tolerance issues that are frequently observed with repeated administration of GPCR agonists.
Collapse
Affiliation(s)
- Kari A Johnson
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, United States
| |
Collapse
|
8
|
Khoo SYS, LeCocq MR, Deyab GE, Chaudhri N. Context and topography determine the role of basolateral amygdala metabotropic glutamate receptor 5 in appetitive Pavlovian responding. Neuropsychopharmacology 2019; 44:1524-1533. [PMID: 30758331 PMCID: PMC6785093 DOI: 10.1038/s41386-019-0335-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/28/2019] [Accepted: 02/03/2019] [Indexed: 01/10/2023]
Abstract
Preclinical data have shown that the excitatory metabotropic Gαq-coupled glutamate receptor, mGluR5, has a role in substance abuse and relapse. However, little is known about the contribution of mGluR5 to the expression of conditioned responding elicited by appetitive Pavlovian cues. We investigated this question in rats that were trained to associate a discrete, auditory conditioned stimulus (CS) with a fructose-glucose solution (5.5% fructose/4.5% glucose; "sugar"). In subsequent tests for the expression of conditioned responding without sugar delivery, CS-elicited fluid port entries were elevated in a context associated with sugar, relative to an equally familiar, neutral context. Inhibiting mGluR5 via systemic injections of a negative allosteric modulator (MTEP; 5 mg/kg) reduced CS port entries in both the sugar context and neutral context. Targeting MTEP microinjections (3 µg/side; 0.3 µl/min) to the nucleus accumbens (Acb) core had no effect on CS port entries at test, whereas the same manipulation in the basolateral amygdala (BLA) produced effects that were topographically dependent. Specifically, microinjecting MTEP in the posterior BLA had no effect on behavior, whereas inhibiting mGluR5 in the anterior BLA enhanced the contextual discrimination of CS port entries. These data are the first to show a role of mGluR5 in the context-dependent expression of appetitive Pavlovian conditioned responding, with a topographically defined arrangement of mGluR5 in the BLA being particularly important for context-based responding to a discrete, appetitive cue.
Collapse
Affiliation(s)
- Shaun Yon-Seng Khoo
- 0000 0004 1936 8630grid.410319.eCenter for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Department of Psychology, Concordia University, Quebec, Montreal, Canada
| | - Mandy Rita LeCocq
- 0000 0004 1936 8630grid.410319.eCenter for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Department of Psychology, Concordia University, Quebec, Montreal, Canada
| | - Ghislaine E. Deyab
- 0000 0004 1936 8630grid.410319.eCenter for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Department of Psychology, Concordia University, Quebec, Montreal, Canada
| | - Nadia Chaudhri
- Center for Studies in Behavioral Neurobiology/FRQS Groupe de recherche en neurobiologie comportementale, Department of Psychology, Concordia University, Quebec, Montreal, Canada.
| |
Collapse
|
9
|
Kasten CR, Holmgren EB, Wills TA. Metabotropic Glutamate Receptor Subtype 5 in Alcohol-Induced Negative Affect. Brain Sci 2019; 9:E183. [PMID: 31366097 PMCID: PMC6721373 DOI: 10.3390/brainsci9080183] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/26/2019] [Accepted: 07/28/2019] [Indexed: 02/07/2023] Open
Abstract
Allosteric modulators of metabotropic glutamate 5 receptors (mGlu5 receptors) have been identified as a promising treatment to independently alleviate both negative affective states and ethanol-seeking and intake. However, these conditions are often comorbid and might precipitate one another. Acute and protracted ethanol withdrawal can lead to negative affective states. In turn, these states are primary drivers of alcohol relapse, particularly among women. The current review synthesizes preclinical studies that have observed the role of mGlu5 receptor modulation in negative affective states following ethanol exposure. The primary behavioral assays discussed are ethanol-seeking and intake, development and extinction of ethanol-associated cues and contexts, behavioral despair, and anxiety-like activity. The work done to-date supports mGlu5 receptor modulation as a promising target for mediating negative affective states to reduce ethanol intake or prevent relapse. Limitations in interpreting these data include the lack of models that use alcohol-dependent animals, limited use of adolescent and female subjects, and a lack of comprehensive evaluations of negative affective-like behavior.
Collapse
Affiliation(s)
- Chelsea R Kasten
- LSU Health Sciences Center-New Orleans, Department of Cell Biology and Anatomy, Medical Education Building, 1901 Perdido Street, Room 6103, New Orleans, LA 70112, USA
| | - Eleanor B Holmgren
- LSU Health Sciences Center-New Orleans, Department of Cell Biology and Anatomy, Medical Education Building, 1901 Perdido Street, Room 6103, New Orleans, LA 70112, USA
| | - Tiffany A Wills
- LSU Health Sciences Center-New Orleans, Department of Cell Biology and Anatomy, Medical Education Building, 1901 Perdido Street, Room 6103, New Orleans, LA 70112, USA.
| |
Collapse
|
10
|
Lee KM, Coelho MA, Class MA, Sern KR, Bocz MD, Szumlinski KK. mGlu5 Receptor Blockade Within the Nucleus Accumbens Shell Reduces Behavioral Indices of Alcohol Withdrawal-Induced Anxiety in Mice. Front Pharmacol 2018; 9:1306. [PMID: 30483137 PMCID: PMC6243038 DOI: 10.3389/fphar.2018.01306] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 10/25/2018] [Indexed: 11/13/2022] Open
Abstract
Withdrawal from binge-drinking increases negative affect, coinciding with increased expression of the metabotropic glutamate receptor 5 (mGlu5) within the shell of the nucleus accumbens (AcbSh). Supporting a causal-effect relationship, systemic treatment with the mGlu5 receptor antagonist MTEP [3-((2-Methyl-4-thiazolyl)ethynyl)pyridine] is anxiolytic in binge-drinking adult and adolescent mice. Here, we employed neuropharmacological approaches to examine the functional relevance of AcbSh mGlu5 for behavioral indices of alcohol withdrawal-induced hyper-anxiety. Adult (PND 56) and adolescent (PND 28) male C57BL/6J mice consumed alcohol under modified Drinking-in-the-Dark procedures (10, 20, and 40% alcohol v/v) for 14 days. At an alcohol withdrawal time-point when mice manifest robust behavioral signs of hyper-anxiety (1 and 28 days withdrawal for adults and adolescents, respectively), mice were infused intra-AcbSh with 0, 1 or 10 μg MTEP and then affect was assayed in the light-dark shuttle box, marble-burying and forced swim tests. Brain tissue was collected to evaluate changes in Egr1 (early growth response protein 1) induction to index AcbSh neuronal activity. As expected, alcohol-experienced mice exhibited behavioral signs of hyper-emotionality. The anxiolytic effects of intra-AchSh MTEP were modest, but dose-dependent, and varied with age of drinking-onset. In adult-onset mice, only the 1 μg MTEP dose reduced withdrawal-induced hyper-anxiety, whereas only the higher dose was effective in adolescent-onset animals. MTEP reduced Egr1 expression within the AcbSh, irrespective of alcohol drinking history or age of drinking-onset. However, only the high MTEP dose reduced Egr1 expression in adolescent-onset binging mice. These results implicate AcbSh mGlu5 in modulating alcohol withdrawal-induced negative affect and suggest age differences in the neurobiological effects of alcohol withdrawal and behavioral responsiveness to mGlu5 blockade within the AcbSh.
Collapse
Affiliation(s)
- Kaziya M. Lee
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Michal A. Coelho
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - MacKayla A. Class
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Kimberly R. Sern
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Mark D. Bocz
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Karen K. Szumlinski
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
| |
Collapse
|
11
|
Role of glutamatergic system and mesocorticolimbic circuits in alcohol dependence. Prog Neurobiol 2018; 171:32-49. [PMID: 30316901 DOI: 10.1016/j.pneurobio.2018.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/08/2018] [Accepted: 10/08/2018] [Indexed: 02/06/2023]
Abstract
Emerging evidence demonstrates that alcohol dependence is associated with dysregulation of several neurotransmitters. Alterations in dopamine, glutamate and gamma-aminobutyric acid release are linked to chronic alcohol exposure. The effects of alcohol on the glutamatergic system in the mesocorticolimbic areas have been investigated extensively. Several studies have demonstrated dysregulation in the glutamatergic systems in animal models exposed to alcohol. Alcohol exposure can lead to an increase in extracellular glutamate concentrations in mesocorticolimbic brain regions. In addition, alcohol exposure affects the expression and functions of several glutamate receptors and glutamate transporters in these brain regions. In this review, we discussed the effects of alcohol exposure on glutamate receptors, glutamate transporters and glutamate homeostasis in each area of the mesocorticolimbic system. In addition, we discussed the genetic aspect of alcohol associated with glutamate and reward circuitry. We also discussed the potential therapeutic role of glutamate receptors and glutamate transporters in each brain region for the treatment of alcohol dependence. Finally, we provided some limitations on targeting the glutamatergic system for potential therapeutic options for the treatment alcohol use disorders.
Collapse
|
12
|
Joffe ME, Centanni SW, Jaramillo AA, Winder DG, Conn PJ. Metabotropic Glutamate Receptors in Alcohol Use Disorder: Physiology, Plasticity, and Promising Pharmacotherapies. ACS Chem Neurosci 2018; 9:2188-2204. [PMID: 29792024 PMCID: PMC6192262 DOI: 10.1021/acschemneuro.8b00200] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Developing efficacious treatments for alcohol use disorder (AUD) has proven difficult. The insidious nature of the disease necessitates a deep understanding of its underlying biology as well as innovative approaches to ameliorate ethanol-related pathophysiology. Excessive ethanol seeking and relapse are generated by long-term changes to membrane properties, synaptic physiology, and plasticity throughout the limbic system and associated brain structures. Each of these factors can be modulated by metabotropic glutamate (mGlu) receptors, a diverse set of G protein-coupled receptors highly expressed throughout the central nervous system. Here, we discuss how different components of the mGlu receptor family modulate neurotransmission in the limbic system and other brain regions involved in AUD etiology. We then describe how these processes are dysregulated following ethanol exposure and speculate about how mGlu receptor modulation might restore such pathophysiological changes. To that end, we detail the current understanding of the behavioral pharmacology of mGlu receptor-directed drug-like molecules in animal models of AUD. Together, this review highlights the prominent position of the mGlu receptor system in the pathophysiology of AUD and provides encouragement that several classes of mGlu receptor modulators may be translated as viable treatment options.
Collapse
Affiliation(s)
- Max E. Joffe
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
| | - Samuel W. Centanni
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Anel A. Jaramillo
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - Danny G. Winder
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37212, United States
| | - P. Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, Tennessee 37232-0697, United States
| |
Collapse
|
13
|
Lee KM, Coelho MA, Class MA, Szumlinski KK. mGlu5-dependent modulation of anxiety during early withdrawal from binge-drinking in adult and adolescent male mice. Drug Alcohol Depend 2018; 184:1-11. [PMID: 29324247 PMCID: PMC6371787 DOI: 10.1016/j.drugalcdep.2017.10.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 10/26/2017] [Accepted: 10/29/2017] [Indexed: 10/18/2022]
Abstract
Binge alcohol-drinking elicits symptoms of negative affect such as anxiety upon cessation, which is a source of negative reinforcement for perpetuating this pattern of alcohol abuse. Binge-induced anxiety during early (24 h) withdrawal is associated with increased expression of metabotropic glutamate receptor 5 (mGlu5) within the nucleus accumbens shell (AcbSh) of adult male mice, but was unchanged in anxiety-resilient adolescents. Herein, we determined the role of mGlu5 signaling in withdrawal-induced anxiety via pharmacological manipulation using the mGlu5 negative allosteric modulator MTEP and the positive allosteric modulator CDPPB. Adult (PND 56) and adolescent (PND 28) male C57BL/6J mice binge-drank for 14 days under 3-bottle-choice procedures for 2 h/day; control animals drank water only. Approximately 24 h following the final alcohol presentation, animals were treated with 30 mg/kg IP MTEP, CDPPB, or vehicle and then tested, thirty minutes later, for behavioral signs of anxiety. Vehicle-treated binge-drinking adults exhibited hyperanxiety in all paradigms, while vehicle-treated binge-drinking adolescents did not exhibit withdrawal-induced anxiety. In adults, 30 mg/kg MTEP decreased alcohol-induced anxiety across paradigms, while 3 mg/kg MTEP was anxiolytic in adult water controls. CDPPB was modestly anxiogenic in both alcohol- and water-drinking mice. Adolescent animals showed minimal response to either CDPPB or MTEP, suggesting that anxiety in adolescence may be mGlu5-independent. These results demonstrate a causal role for mGlu5 in withdrawal-induced anxiety in adults and suggest age-related differences in the behavioral pharmacology of the negative reinforcing properties of alcohol.
Collapse
Affiliation(s)
- Kaziya M. Lee
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - Michal A. Coelho
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA
| | - MacKayla A. Class
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA,Department of Molecular, Cellular and Developmental Biology and the Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, 93106-9625, USA
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA,Department of Molecular, Cellular and Developmental Biology and the Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, 93106-9625, USA,Corresponding author at: University of California Santa Barbara, Santa Barbara, CA, 93106-9660, USA. (K.K. Szumlinski)
| |
Collapse
|
14
|
Akkus F, Mihov Y, Treyer V, Ametamey SM, Johayem A, Senn S, Rösner S, Buck A, Hasler G. Metabotropic glutamate receptor 5 binding in male patients with alcohol use disorder. Transl Psychiatry 2018; 8:17. [PMID: 29317611 PMCID: PMC5802584 DOI: 10.1038/s41398-017-0066-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/13/2017] [Accepted: 10/26/2017] [Indexed: 01/30/2023] Open
Abstract
Glutamate signaling plays a major role in addiction. Preclinical research strongly suggests an implication of G-protein-coupled metabotropic glutamate receptor subtype 5 (mGluR5) in nicotine addiction and alcohol use disorder. In humans, smoking is related to a global reduction in mGluR5 availability. In the present study, we investigated mGluR5 in vivo in patients with alcohol use disorder without the confounding effects of smoking. A total of 14 male subjects with alcohol use disorder and at least a 25-day abstinence and 14 matched male non-smoking healthy controls were included in the study. We employed positron emission tomography (PET) with the mGluR5-specific radiotracer [11C]ABP688, using a bolus/infusion protocol. We found increased mGluR5 DVR in several regions within the temporal lobe in patients, as compared to controls. The largest between-group difference was in the amygdala. There was a marked positive relation between mGluR5 DVR in the anterior cingulate and mGluR5 DVR in the orbitofrontal cortex in patients, but not in controls. In patients, lower temptation to drink was related to higher amygdala mGluR5 DVR. We did not find altered mGluR5 DVR in the basal ganglia of subjects recovering from alcohol use disorder. In conclusion, our study provides clinical evidence for altered mGluR5 signaling in the amygdala in alcohol use disorder. This alteration was associated with the temptation to drink. In addition, this study suggests abnormal mGluR5 signaling in a network underlying reward-related behavioral flexibility. These findings strengthen the case for pharmacological agents acting on mGluR5 as promising candidates for the treatment of alcohol use disorder.
Collapse
Affiliation(s)
- Funda Akkus
- Division of Molecular Psychiatry, Translational Research Center, University Hospital of Psychiatry, University of Bern, 3000, Bern 60, Switzerland
| | - Yoan Mihov
- Division of Molecular Psychiatry, Translational Research Center, University Hospital of Psychiatry, University of Bern, 3000, Bern 60, Switzerland
| | - Valerie Treyer
- PET Center, Division of Nuclear Medicine, University Hospital, 8091, Zurich, Switzerland
| | - Simon M Ametamey
- Center for Radiopharmaceutical Science of ETH, PSI, and USZ, Department of Chemistry and Applied Biosciences of ETH, 8093, Zurich, Switzerland
| | - Anass Johayem
- PET Center, Division of Nuclear Medicine, University Hospital, 8091, Zurich, Switzerland
| | - Smeralda Senn
- Forel Clinic, Addiction Treatment Center, 8548, Ellikon an der Thur, Switzerland
| | - Susanne Rösner
- Forel Clinic, Addiction Treatment Center, 8548, Ellikon an der Thur, Switzerland
| | - Alfred Buck
- PET Center, Division of Nuclear Medicine, University Hospital, 8091, Zurich, Switzerland
| | - Gregor Hasler
- Division of Molecular Psychiatry, Translational Research Center, University Hospital of Psychiatry, University of Bern, 3000, Bern 60, Switzerland.
| |
Collapse
|
15
|
Cannady R, Fisher KR, Graham C, Crayle J, Besheer J, Hodge CW. Potentiation of amygdala AMPA receptor activity selectively promotes escalated alcohol self-administration in a CaMKII-dependent manner. Addict Biol 2017; 22:652-664. [PMID: 26742808 DOI: 10.1111/adb.12357] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/30/2015] [Accepted: 11/30/2015] [Indexed: 12/21/2022]
Abstract
Growing evidence indicates that drugs of abuse gain control over the individual by usurping glutamate-linked mechanisms of neuroplasticity in reward-related brain regions. Accordingly, we have shown that glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) activity in the amygdala is required for the positive reinforcing effects of alcohol, which underlie the initial stages of addiction. It is unknown, however, if enhanced AMPAR activity in the amygdala facilitates alcohol self-administration, which is a kernel premise of glutamate hypotheses of addiction. Here, we show that low-dose alcohol (0.6 g/kg/30 minutes) self-administration increases phosphorylation (activation) of AMPAR subtype GluA1 S831 (pGluA1 S831) in the central amygdala (CeA), basolateral amygdala and nucleus accumbens core (AcbC) of selectively bred alcohol-preferring P-rats as compared with behavior-matched (non-drug) sucrose controls. The functional role of enhanced AMPAR activity was assessed via site-specific infusion of the AMPAR positive modulator, aniracetam, in the CeA and AcbC prior to alcohol self-administration. Intra-CeA aniracetam increased alcohol-reinforced but not sucrose-reinforced responding and was ineffective following intra-AcbC infusion. Because GluA1 S831 is a Ca2+/calmodulin-dependent protein kinase II (CaMKII) substrate, we sought to determine if AMPAR regulation of enhanced alcohol self-administration is dependent on CaMKII activity. Intra-CeA infusion of the cell-permeable CaMKII peptide inhibitor myristolated autocamtide-2-related inhibitory peptide (m-AIP) dose-dependently reduced alcohol self-administration. A subthreshold dose of m-AIP also blocked the aniracetam-induced escalation of alcohol self-administration, demonstrating that AMPAR-mediated potentiation of alcohol reinforcement requires CaMKII activity in the amygdala. Enhanced activity of plasticity-linked AMPAR-CaMKII signaling in the amygdala may promote escalated alcohol use via increased positive reinforcement during the initial stages of addiction.
Collapse
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
| | - Kristen R. Fisher
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Caitlin Graham
- Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Jesse Crayle
- Bowles Center for Alcohol Studies; 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
| | - 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
| |
Collapse
|
16
|
Goodwani S, Saternos H, Alasmari F, Sari Y. Metabotropic and ionotropic glutamate receptors as potential targets for the treatment of alcohol use disorder. Neurosci Biobehav Rev 2017; 77:14-31. [PMID: 28242339 DOI: 10.1016/j.neubiorev.2017.02.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/13/2017] [Accepted: 02/22/2017] [Indexed: 12/16/2022]
Abstract
Emerging evidence indicates that dysfunctional glutamate neurotransmission is critical in the initiation and development of alcohol and drug dependence. Alcohol consumption induced downregulation of glutamate transporter 1 (GLT-1) as reported in previous studies from our laboratory. Glutamate is the major excitatory neurotransmitter in the brain, which acts via interactions with several glutamate receptors. Alcohol consumption interferes with the glutamatergic signal transmission by altering the functions of these receptors. Among the glutamate receptors involved in alcohol-drinking behavior are the metabotropic receptors such as mGluR1/5, mGluR2/3, and mGluR7, as well as the ionotropic receptors, NMDA and AMPA. Preclinical studies using agonists and antagonists implicate these glutamatergic receptors in the development of alcohol use disorder (AUD). Therefore, the purpose of this review is to discuss the neurocircuitry involving glutamate transmission in animals exposed to alcohol and further outline the role of metabotropic and ionotropic receptors in the regulation of alcohol-drinking behavior. This review provides ample information about the potential therapeutic role of glutamatergic receptors for the treatment of AUD.
Collapse
Affiliation(s)
- Sunil Goodwani
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA; The Neurodegeneration Consortium, Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center, Houston, TX, 77054, USA
| | - Hannah Saternos
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Fawaz Alasmari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Youssef Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA.
| |
Collapse
|
17
|
Emmitte KA. mGlu5negative allosteric modulators: a patent review (2013 - 2016). Expert Opin Ther Pat 2017; 27:691-706. [DOI: 10.1080/13543776.2017.1280466] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
| |
Collapse
|
18
|
Lee KM, Coelho MA, McGregor HA, Solton NR, Cohen M, Szumlinski KK. Adolescent Mice Are Resilient to Alcohol Withdrawal-Induced Anxiety and Changes in Indices of Glutamate Function within the Nucleus Accumbens. Front Cell Neurosci 2016; 10:265. [PMID: 27917110 PMCID: PMC5114265 DOI: 10.3389/fncel.2016.00265] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 10/31/2016] [Indexed: 11/13/2022] Open
Abstract
Binge-drinking is the most prevalent form of alcohol abuse and while an early life history of binge-drinking is a significant risk factor for subsequent alcoholism and co-morbid affective disorders, relatively little is known regarding the biobehavioral impact of binge-drinking during the sensitive neurodevelopmental period of adolescence. In adult mice, a month-long history of binge-drinking elicits a hyper-glutamatergic state within the nucleus accumbens (Acb), coinciding with hyper-anxiety. Herein, we employed a murine model of binge-drinking to determine whether or not: (1) withdrawal-induced changes in brain and behavior differ between adult and adolescent bingers; and (2) increased behavioral signs of negative affect and changes in Acb expression of glutamate-related proteins would be apparent in adult mice with less chronic binge-drinking experience (14 days, approximating the duration of mouse adolescence). Adult and adolescent male C57BL/6J mice were subjected to a 14-day binge-drinking protocol (5, 10, 20 and 40% alcohol (v/v) for 2 h/day), while age-matched controls received water. At 24 h withdrawal, half of the animals from each group were assayed for negative affect, while tissue was sampled from the shell (AcbSh) and core (AcbC) subregions of the remaining mice for immunoblotting analyses. Adult bingers exhibited hyper-anxiety when tested for defensive marble burying. Additionally, adult bingers showed increased mGlu1, mGlu5, and GluN2b expression in the AcbSh and PKCε and CAMKII in the AcbC. Compared to adults, adolescent mice exhibited higher alcohol intake and blood alcohol concentrations (BACs); however, adolescent bingers did not show increased anxiety in the marble-burying test. Furthermore, adolescent bingers also failed to exhibit the same alcohol-induced changes in mGlu and kinase protein expression seen in the adult bingers. Irrespective of age, bingers exhibited behavioral hyperactivity in the forced swim test (FST) compared to water drinkers, which was paralleled by an increase in AcbC levels of GluN2b. Thus, a 2-week period of binge-drinking is sufficient to produce a hyper-anxious state and related increases in protein indices of Acb glutamate function. In contrast, adolescents were resilient to many of the effects of early alcohol withdrawal and this attenuated sensitivity to the negative consequences of binge drinking may facilitate greater alcohol intake in adolescent drinkers.
Collapse
Affiliation(s)
- Kaziya M. Lee
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
| | - Michal A. Coelho
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
| | - Hadley A. McGregor
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
| | - Noah R. Solton
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
| | - Matan Cohen
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa BarbaraSanta Barbara, CA, USA
- Department of Molecular, Cellular and Developmental Biology and the Neuroscience Research Institute, University of California Santa BarbaraSanta Barbara, CA, USA
| |
Collapse
|
19
|
Schwendt M, Olive MF. Protein kinase Cɛ activity regulates mGluR5 surface expression in the rat nucleus accumbens. J Neurosci Res 2016; 95:1079-1090. [PMID: 27546836 DOI: 10.1002/jnr.23868] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 06/29/2016] [Accepted: 07/12/2016] [Indexed: 12/11/2022]
Abstract
Type 5 metabotropic glutamate receptors (mGluR5) activate protein kinase C (PKC) via coupling to Gαq/11 protein signaling. We have previously demonstrated that the epsilon isoform of PKC (PKCɛ) is a critical downstream target of mGluR5 in regulating behavioral and biochemical responses to alcohol. Recent evidence suggests that PKC-mediated phosphorylation of mGluR5 can lead to receptor desensitization and internalization. We therefore sought to examine the specific involvement of PKCɛ in the regulation of mGluR5 surface expression in the nucleus accumbens (NAc), a key regulator of alcohol-associated behaviors. Coronal brain sections from male Wistar rats were analyzed for either colocalization of mGluR5 and PKCɛ via immunohistochemistry or changes in mGluR5 surface expression and PKCɛ phosphorylation following local application of PKCɛ translocation activator or inhibitor peptides and/or an orthosteric mGluR5 agonist. We observed colocalization of mGluR5 and PKCɛ in the NAc. We also showed that intra-NAc infusion of the PKCɛ translocation inhibitor ɛV1-2 increased mGluR5 surface expression under baseline conditions. Stimulation of mGluR5 with an orthosteric agonist DHPG, dose dependently increased ERK1/2 and PKCɛ phosphorylation as well as mGluR5 internalization in acute NAc slices. Finally, we observed that activation of PKCɛ translocation with Tat-ΨɛRACK peptide mediates agonist-independent mGluR5 internalization, whereas PKCɛ translocation inhibitor ɛV1-2 prevents agonist-dependent internalization of mGluR5 in NAc slice preparations. These findings suggest that the subcellular localization of mGluR5 in the NAc is regulated by PKCɛ under basal and stimulation conditions, which may influence the role of mGluR5-PKCɛ signaling in alcohol-related behaviors. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Marek Schwendt
- Psychology Department, University of Florida, Gainesville, Florida
| | - M Foster Olive
- Psychology Department, Arizona State University, Tempe, Arizona
| |
Collapse
|
20
|
Cozzoli DK, Courson J, Rostock C, Campbell RR, Wroten MG, McGregor H, Caruana AL, Miller BW, Hu JH, Zhang PW, Xiao B, Worley PF, Crabbe JC, Finn DA, Szumlinski KK. Protein Kinase C Epsilon Activity in the Nucleus Accumbens and Central Nucleus of the Amygdala Mediates Binge Alcohol Consumption. Biol Psychiatry 2016; 79:443-51. [PMID: 25861702 PMCID: PMC4561036 DOI: 10.1016/j.biopsych.2015.01.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 01/09/2015] [Accepted: 01/20/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Protein kinase C epsilon (PKCε) is emerging as a potential target for the development of pharmacotherapies to treat alcohol use disorders, yet little is known regarding how a history of a highly prevalent form of drinking, binge alcohol intake, influences enzyme priming or the functional relevance of kinase activity for excessive alcohol intake. METHODS Immunoblotting was employed on tissue from subregions of the nucleus accumbens (NAc) and the amygdala to examine both idiopathic and binge drinking-induced changes in constitutive PKCε priming. The functional relevance of PKCε translocation for binge drinking and determination of potential upstream signaling pathways involved were investigated using neuropharmacologic approaches within the context of two distinct binge drinking procedures, drinking in the dark and scheduled high alcohol consumption. RESULTS Binge alcohol drinking elevated p(Ser729)-PKCε levels in both the NAc and the central nucleus of the amygdala (CeA). Moreover, immunoblotting studies of selectively bred and transgenic mouse lines revealed a positive correlation between the propensity to binge drink alcohol and constitutive p(Ser729)-PKCε levels in the NAc and CeA. Finally, neuropharmacologic inhibition of PKCε translocation within both regions reduced binge alcohol consumption in a manner requiring intact group 1 metabotropic glutamate receptors, Homer2, phospholipase C, and/or phosphotidylinositide-3 kinase function. CONCLUSIONS Taken together, these data indicate that PKCε signaling in both the NAc and CeA is a major contributor to binge alcohol drinking and to the genetic propensity to consume excessive amounts of alcohol.
Collapse
Affiliation(s)
- Debra K. Cozzoli
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A,Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Justin Courson
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Charlotte Rostock
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Rianne R. Campbell
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Melissa G. Wroten
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Hadley McGregor
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Amanda L. Caruana
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Bailey W. Miller
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Jia-Hua Hu
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Ping Wu Zhang
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Bo Xiao
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Paul F. Worley
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - John C. Crabbe
- Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Deborah A. Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| |
Collapse
|
21
|
Blasio A, Messing RO. Binge Drinking With Protein Kinase C Epsilon: A Role for Mammalian Target of Rapamycin Complex 2? Biol Psychiatry 2016; 79:425-6. [PMID: 26893192 PMCID: PMC4909116 DOI: 10.1016/j.biopsych.2015.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 12/15/2015] [Indexed: 11/18/2022]
Affiliation(s)
- Angelo Blasio
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, Texas
| | - Robert O Messing
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, Texas.
| |
Collapse
|
22
|
N-Alkylpyrido[1',2':1,5]pyrazolo-[4,3-d]pyrimidin-4-amines: A new series of negative allosteric modulators of mGlu1/5 with CNS exposure in rodents. Bioorg Med Chem Lett 2016; 26:1894-900. [PMID: 26988308 DOI: 10.1016/j.bmcl.2016.03.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/07/2016] [Accepted: 03/08/2016] [Indexed: 11/20/2022]
Abstract
Selective negative allosteric modulators (NAMs) of each of the group I metabotropic glutamate receptors (mGlu1 and mGlu5) have been well characterized in the literature and offer potential as therapeutics in several disorders of the central nervous system (CNS). Still, compounds that are potent mGlu1/5 NAMs with selectivity versus the other six members of the mGlu family as well as the balance of properties required for use in vivo are lacking. A medicinal chemistry effort centered on the identification of a lead series with the potential of delivering such compounds is described in this Letter. Specifically, a new class of pyrido[1',2':1,5]pyrazolo[4,3-d]pyrimidin-4-amines was designed as a novel isosteric replacement for 4-aminoquinazolines, and compounds from within this chemotype exhibited dual NAM activity at both group I mGlus. One compound, VU0467558 (29), demonstrated near equipotent activity at both receptors, selectivity versus other mGlus, a favorable ancillary pharmacology profile, and CNS exposure in rodents.
Collapse
|
23
|
Gibula-Bruzda E, Marszalek-Grabska M, Gawel K, Witkowska E, Izdebski J, Kotlinska JH. The influence of the new enkephalin derivative, cyclo[N(ε),N(β)-carbonyl-d-Lys(2),Dap(5)] enkephalinamide (cUENK6), on reinstatement of ethanol-induced conditioned place preference in rats. Physiol Behav 2015; 145:50-6. [PMID: 25817357 DOI: 10.1016/j.physbeh.2015.03.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/18/2015] [Accepted: 03/24/2015] [Indexed: 11/28/2022]
Abstract
The aim of the present study was to determine whether a new cyclic analog of enkephalin, cyclo[N(ε),N(β)-carbonyl-d-Lys(2),Dap(5)] enkephalinamide (cUENK6), a preferential μ-(MORs), and, to a lower extent, a δ-opioid receptor (DORs) agonist in vitro, could reinstate ethanol-induced conditioned place preference (CPP). In our work, male Wistar rats were first conditioned either with ethanol (10% w/v, 0.5g/kg, intraperitoneally (i.p.)) or 0.9% NaCl in a biased CPP procedure. The intracerebroventricular (i.c.v.) administration of DORs antagonist (naltrindole, 2.5 and 5nmol) or MORs antagonist (β-funaltrexamine, 5 and 10nmol), but not the κ opioid receptor (KORs) antagonist (norbinaltorphimine, 5 and 10nmol) was then administered and inhibited the expression of ethanol-induced CPP. After the extinction session, i.c.v. administration of cUENK6 at the dose of 0.125, 0.25 and 0.5nmol occurred, and was found to reinstate the ethanol-induced CPP similar to that of the priming injection of ethanol. However, the reinstated effect of cUENK6 (0.25nmol) was strongly abolished by administration of naltrindole and, to lesser extent, by β-funaltrexamine. Furthermore, the preferential MORs agonist-morphine (13nmol, i.c.v.) and the DORs agonist-[Leu(5)]-enkephalin (2.7 and 5.4nmol, i.c.v.) also reinstated the ethanol-induced CPP. cUENK6 given alone at the dose of 0.25nmol before the testing phase had no effect in animals that received 0.9% NaCl during the conditioning phase and also did not influence their locomotor activity. These data suggest that the effects of cUENK6 did not have an impact on the results obtained in the reinstatement procedure of CPP. Overall, the data support the idea that both MORs and DORs are normally involved in the expression and reinstatement of ethanol conditioned seeking behavior - as indexed by CPP in rats.
Collapse
Affiliation(s)
- Ewa Gibula-Bruzda
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland.
| | | | - Kinga Gawel
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| | - Ewa Witkowska
- Laboratory of Peptides, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Jan Izdebski
- Laboratory of Peptides, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Jolanta H Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Lublin, Poland
| |
Collapse
|
24
|
Roohi N, Sarihi A, Shahidi S, Zarei M, Haghparast A. Microinjection of the mGluR5 antagonist MTEP into the nucleus accumbens attenuates the acquisition but not expression of morphine-induced conditioned place preference in rats. Pharmacol Biochem Behav 2014; 126:109-15. [DOI: 10.1016/j.pbb.2014.09.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/18/2014] [Accepted: 09/26/2014] [Indexed: 02/03/2023]
|
25
|
Bates BS, Rodriguez AL, Felts AS, Morrison RD, Venable DF, Blobaum AL, Byers FW, Lawson KP, Daniels JS, Niswender CM, Jones CK, Conn PJ, Lindsley CW, Emmitte KA. Discovery of VU0431316: a negative allosteric modulator of mGlu5 with activity in a mouse model of anxiety. Bioorg Med Chem Lett 2014; 24:3307-14. [PMID: 24969015 DOI: 10.1016/j.bmcl.2014.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 05/30/2014] [Accepted: 06/02/2014] [Indexed: 11/30/2022]
Abstract
Development of SAR in an aryl ether series of mGlu5 NAMs leading to the identification of pyrazine analog VU0431316 is described in this Letter. VU0431316 is a potent and selective non-competitive antagonist of mGlu5 that binds at a known allosteric binding site. VU0431316 demonstrates an attractive DMPK profile, including moderate clearance and good bioavailability in rats. Intraperitoneal (IP) dosing of VU0431316 in a mouse marble burying model of anxiety, an assay known to be sensitive to mGlu5 antagonists and other anxiolytics, produced dose proportional effects.
Collapse
Affiliation(s)
- Brittney S Bates
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alice L Rodriguez
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Andrew S Felts
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ryan D Morrison
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Daryl F Venable
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Anna L Blobaum
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Frank W Byers
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kera P Lawson
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - J Scott Daniels
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Colleen M Niswender
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Carrie K Jones
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Tennessee Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, TN 37212, USA
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Kyle A Emmitte
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA.
| |
Collapse
|
26
|
Increased extracellular glutamate in the nucleus accumbens promotes excessive ethanol drinking in ethanol dependent mice. Neuropsychopharmacology 2014; 39:707-17. [PMID: 24067300 PMCID: PMC3895249 DOI: 10.1038/npp.2013.256] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 08/02/2013] [Accepted: 08/12/2013] [Indexed: 12/20/2022]
Abstract
Using a well-established model of ethanol dependence and relapse, this study examined adaptations in glutamatergic transmission in the nucleus accumbens (NAc) and their role in regulating voluntary ethanol drinking. Mice were first trained to drink ethanol in a free-choice, limited access (2 h/day) paradigm. One group (EtOH mice) received repeated weekly cycles of chronic intermittent ethanol (CIE) exposure with intervening weeks of test drinking sessions, whereas the remaining mice (CTL mice) were similarly treated but did not receive CIE treatment. Over repeated cycles of CIE exposure, EtOH mice exhibited significant escalation in drinking (up to ∼3.5 g/kg), whereas drinking remained relatively stable at baseline levels (2-2.5 g/kg) in CTL mice. Using in vivo microdialysis procedures, extracellular glutamate (GLUEX) levels in the NAc were increased approximately twofold in EtOH mice compared with CTL mice, and this difference was observed 7 days after final CIE exposure, indicating that this hyperglutamatergic state persisted beyond acute withdrawal. This finding prompted additional studies examining the effects of pharmacologically manipulating GLUEX in the NAc on ethanol drinking in the CIE model. The non-selective glutamate reuptake antagonist, threo-β-benzyloxyaspartate (TBOA), was bilaterally microinjected into the NAc and found to dose-dependently increase drinking in nondependent (CTL) mice to levels attained by dependent (EtOH) mice. TBOA also further increased drinking in EtOH mice. In contrast, reducing glutamatergic transmission in the NAc via bilateral injections of the metabotropic glutamate receptor-2/3 agonist LY379268 reduced drinking in dependent (EtOH) mice to nondependent (CTL) levels, whereas having a more modest effect in decreasing ethanol consumption in CTL mice. Taken together, these data support an important role of glutamatergic transmission in the NAc in regulating ethanol drinking. Additionally, these results indicate that ethanol dependence produces adaptations that favor elevated glutamate activity in the NAc which, in turn, promote excessive levels of ethanol consumption associated with dependence.
Collapse
|
27
|
Lum EN, Campbell RR, Rostock C, Szumlinski KK. mGluR1 within the nucleus accumbens regulates alcohol intake in mice under limited-access conditions. Neuropharmacology 2014; 79:679-87. [PMID: 24467847 DOI: 10.1016/j.neuropharm.2014.01.024] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 12/31/2013] [Accepted: 01/11/2014] [Indexed: 02/05/2023]
Abstract
Idiopathic or alcohol-induced increases in the expression and function of the Group1 metabotropic glutamate receptor subtype 1 (mGluR1) within the extended amygdala are theorized to contribute to an individual's propensity to consume excessive amounts of alcohol. In the past, the detailed study of the functional relevance of mGluR1 for alcoholism-related behaviors in animal models was hampered by the poor solubility and non-specific side effects of available inhibitors; however, the advent of the highly potent and soluble mGluR1 negative allosteric modulator JNJ-16259685 [(3,4-Dihydro-2H-pyrano[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone] has instigated a re-examination of the role for this mGluR subtype in mediating the behavioral effects of alcohol. In this regard, systemic pretreatment with JNJ-16259685 was proven effective at reducing alcohol reinforcement and motivation for the drug. mGluR1 is a Gαq/o-coupled receptor, the stimulation of which activates phospholipase C (PLC). Thus, the present study investigated potential neuroanatomical substrates and intracellular molecules involved in the ability of JNJ-16259685 to reduce alcohol intake. JNJ-16259685 (0-30 pg/side) was infused into the shell subregion of the nucleus accumbens (NAC) of C57BL/6J and Homer2 knock-out (KO) mice, either alone or in combination with the PLC inhibitor U-73122 (5.8 fg/side). Alcohol intake was then assessed under Drinking-in-the-Dark (DID) procedures. Intra-NAC JNJ-16259685 infusion dose-dependently reduced alcohol consumption by C57BL/6J mice; this effect was not additive with that produced by U-73122, nor was it present in Homer2 KO animals. These data provide novel evidence in support of a critical role for mGluR1-PLC signaling, scaffolded by Homer2, within the NAC shell, in maintaining alcohol consumption under limited access procedures. Such findings have relevance for both the pharmacotherapeutics and pharmacogenetics of risky alcohol drinking and alcoholism.
Collapse
Affiliation(s)
- Emily N Lum
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Rianne R Campbell
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Charlotte Rostock
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Karen K Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA.
| |
Collapse
|
28
|
Knackstedt LA, Trantham-Davidson HL, Schwendt M. The role of ventral and dorsal striatum mGluR5 in relapse to cocaine-seeking and extinction learning. Addict Biol 2014; 19:87-101. [PMID: 23710649 DOI: 10.1111/adb.12061] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cocaine addiction is a chronic, relapsing disease characterized by an inability to regulate drug-seeking behavior. Here we investigated the role of mGluR5 in the ventral and dorsal striatum in regulating cocaine-seeking following both abstinence and extinction. Animals underwent 2 weeks of cocaine self-administration followed by 3 weeks of home-cage abstinence. Animals were then reintroduced to the operant chamber for a context-induced relapse test, followed by 7-10 days of extinction training. Once responding was extinguished, cue-primed reinstatement test was conducted. Both drug-seeking tests were conducted in the presence of either mGluR5 negative allosteric modulator, MTEP or vehicle infused into either the nucleus accumbens (NA) core or dorsolateral striatum (dSTR). We found that MTEP infused in the NA core attenuated both context-induced relapse following abstinence and cue-primed reinstatement following extinction training. Blocking dSTR mGluR5 had no effect on context- or cue-induced cocaine-seeking. However, the intra-dSTR MTEP infusion on the context-induced relapse test day attenuated extinction learning for 4 days after the infusion. Furthermore, mGluR5 surface expression was reduced and LTD was absent in dSTR slices of animals undergoing 3 weeks of abstinence from cocaine but not sucrose self-administration. LTD was restored by bath application of VU-29, a positive allosteric modulator of mGluR5. Bath application of MTEP prevented the induction of LTD in dSTR slices from sucrose animals. Taken together, this data indicates that dSTR mGluR5 plays an essential role in extinction learning but not cocaine relapse, while NA core mGluR5 modulates drug-seeking following both extinction and abstinence from cocaine self-administration.
Collapse
Affiliation(s)
- Lori A. Knackstedt
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| | | | - Marek Schwendt
- Department of Neurosciences; Medical University of South Carolina; Charleston SC USA
| |
Collapse
|
29
|
Cozzoli DK, Strong-Kaufman MN, Tanchuck MA, Hashimoto JG, Wiren KM, Finn DA. The Effect of mGluR5 Antagonism During Binge Drinkingon Subsequent Ethanol Intake in C57BL/6J Mice: Sex- and Age-Induced Differences. Alcohol Clin Exp Res 2013; 38:730-738. [PMID: 27695144 DOI: 10.1111/acer.12292] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Binge ethanol (EtOH) intake during adolescence leads to an array of behavioral and cognitive consequences including elevated intake of EtOH during adulthood, with female mice showing greater susceptibility than males. Administration of the metabotropic glutamate receptor 5 (mGluR5) antagonist 3-((2-Methyl-1,3-thiazol-4-yl)ethynyl)pyridine (MTEP) has been shown to reduce EtOH self-administration in adult male mice, but little is known about its effect on female and adolescent mice. METHODS MTEP (0, 10, 20 mg/kg, i.p.) was repeatedly administered to female and male, adult and adolescent C57BL/6J mice during binge sessions using the scheduled high alcohol consumption paradigm. Next, we assessed whether MTEP administration during binge altered the subsequent 24-hour EtOH intake following a period of abstinence. Finally, we investigated whether MTEP administration during binge followed by an abstinence period altered mRNA of glutamatergic genes within the nucleus accumbens of female mice. RESULTS MTEP significantly decreased binge EtOH intake in all mice, but only female mice exhibited altered subsequent 24-hour EtOH intake. Interestingly, the alteration in subsequent EtOH intake in female animals was age dependent, with adolescent exposure to MTEP during binge decreasing 24-hour intake and adult exposure to MTEP during binge increasing 24-hour intake. Finally, while there were no effects of MTEP pretreatment on the genes examined, there was a robust age effect found during analysis of mGluR1 (Grm1), mGluR5 (Grm5), the NR2A subunit of the NMDA receptor (Grin2a), phosphatidylinositol 3-kinase (Pik3r1), mammalian target of rapamycin (Mtor), and extracellular signal-regulated kinase (Mapk1) mRNA, with adolescent female animals having lower expression than their adult counterparts. CONCLUSIONS Collectively, the present findings add to existing evidence implicating the contribution of long-term effects of adolescent binge drinking to enhance alcohol abuse in adulthood, while suggesting that mGluR5 antagonism may not be the best pharmacotherapy to treat binge alcohol consumption in female and adolescent animals.
Collapse
Affiliation(s)
- Debra K Cozzoli
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| | - Moriah N Strong-Kaufman
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| | - Michelle A Tanchuck
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| | - Joel G Hashimoto
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| | - Kristine M Wiren
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| | - Deborah A Finn
- Department of Behavioral Neuroscience (DKC, MNS-K, MAT, JGH, KMW, DAF), Oregon Health & Science University, Portland, Oregon; Department of Veterans Affairs Medical Research (JGH, KMW, DAF), Veterans Affairs Medical Center, Portland, Oregon; and Portland Alcohol Research Center (DAF), Portland, Oregon
| |
Collapse
|
30
|
Abstract
RATIONALE An increasingly compelling literature points to a major role for the glutamate system in mediating the effects of alcohol on behavior and the pathophysiology of alcoholism. Preclinical studies indicate that glutamate signaling mediates certain aspects of ethanol's intoxicating and rewarding effects, and undergoes adaptations following chronic alcohol exposure that may contribute to the withdrawal, craving and compulsive drug-seeking that drive alcohol abuse and alcoholism. OBJECTIVES We discuss the potential for targeting the glutamate system as a novel pharmacotherapeutic approach to treating alcohol use disorders, focusing on five major components of the glutamate system: the N-methyl-D-aspartate (NMDA) receptor and specific NMDA subunits, the glycineB site on the NMDA receptors (NMDAR), L-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid ionotropic (AMPA) and kainate (KAR) receptors, metabotropic receptors (mGluR), and glutamate transporters. RESULTS Chronic alcohol abuse produces a hyperglutamatergic state, characterized by elevated extracellular glutamate and altered glutamate receptors and transporters. Pharmacologically manipulating glutamatergic neurotransmission alters alcohol-related behaviors including intoxication, withdrawal, and alcohol-seeking, in rodents and human subjects. Blocking NMDA and AMPA receptors reduces alcohol consumption in rodents, but side-effects may limit this as a therapeutic approach. Selectively targeting NMDA and AMPA receptor subunits (e.g., GluN2B, GluA3), or the NMDAR glycineB site offers an alternative approach. Blocking mGluR5 potently affects various alcohol-related behaviors in rodents, and mGluR2/3 agonism also suppresses alcohol consumption. Finally, glutamate transporter upregulation may mitigate behavioral and neurotoxic sequelae of excess glutamate caused by alcohol. CONCLUSIONS Despite the many challenges that remain, targeting the glutamate system offers genuine promise for developing new treatments for alcoholism.
Collapse
|
31
|
Discovery of VU0409106: A negative allosteric modulator of mGlu5 with activity in a mouse model of anxiety. Bioorg Med Chem Lett 2013; 23:5779-85. [PMID: 24074843 DOI: 10.1016/j.bmcl.2013.09.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 08/30/2013] [Accepted: 09/03/2013] [Indexed: 02/06/2023]
Abstract
Development of SAR in an aryl ether series of mGlu5 NAMs leading to the identification of tool compound VU0409106 is described in this Letter. VU0409106 is a potent and selective negative allosteric modulator of mGlu5 that binds at the known allosteric binding site and demonstrates good CNS exposure following intraperitoneal dosing in mice. VU0409106 also proved efficacious in a mouse marble burying model of anxiety, an assay known to be sensitive to mGlu5 antagonists as well as clinically efficacious anxiolytics.
Collapse
|
32
|
Chesworth R, Brown RM, Kim JH, Lawrence AJ. The metabotropic glutamate 5 receptor modulates extinction and reinstatement of methamphetamine-seeking in mice. PLoS One 2013; 8:e68371. [PMID: 23861896 PMCID: PMC3701637 DOI: 10.1371/journal.pone.0068371] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 05/29/2013] [Indexed: 12/12/2022] Open
Abstract
Methamphetamine (METH) is a highly addictive psychostimulant with no therapeutics registered to assist addicts in discontinuing use. Glutamatergic dysfunction has been implicated in the development and maintenance of addiction. We sought to assess the involvement of the metabotropic glutamate 5 receptor (mGlu5) in behaviours relevant to METH addiction because this receptor has been implicated in the actions of other drugs of abuse, including alcohol, cocaine and opiates. mGlu5 knockout (KO) mice were tested in intravenous self-administration, conditioned place preference and locomotor sensitization. Self-administration of sucrose was used to assess the response of KO mice to a natural reward. Acquisition and maintenance of self-administration, as well as the motivation to self-administer METH was intact in mGlu5 KO mice. Importantly, mGlu5 KO mice required more extinction sessions to extinguish the operant response for METH, and exhibited an enhanced propensity to reinstate operant responding following exposure to drug-associated cues. This phenotype was not present when KO mice were tested in an equivalent paradigm assessing operant responding for sucrose. Development of conditioned place preference and locomotor sensitization were intact in KO mice; however, conditioned hyperactivity to the context previously paired with drug was elevated in KO mice. These data demonstrate a role for mGlu5 in the extinction and reinstatement of METH-seeking, and suggests a role for mGlu5 in regulating contextual salience.
Collapse
Affiliation(s)
- Rose Chesworth
- Behavioural Neuroscience Division, Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Robyn M. Brown
- Behavioural Neuroscience Division, Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Jee Hyun Kim
- Behavioural Neuroscience Division, Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Andrew J. Lawrence
- Behavioural Neuroscience Division, Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
| |
Collapse
|
33
|
Abstract
INTRODUCTION The design and development of small molecule negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGlu5) has been an area of intense interest for over a decade. Potential roles have been established for mGlu5 NAMs in the treatment of diseases such as pain, anxiety, gastroesophageal reflux disease (GERD), Parkinson's disease levodopa-induced dyskinesia (PD-LID), fragile X syndrome (FXS), autism, addiction, and depression. AREAS COVERED This review begins with an update of the clinical trial efforts with mGlu5 NAMs. Following that update, the review summarizes small molecule mGlu5 NAM patent applications published between 2010 and 2012. These summaries are subdivided into three separate groups: inventions related to improvements in drug properties and/or developability, new chemical entities that contain a disubstituted alkyne, and new chemical entities that do not contain a disubstituted alkyne. EXPERT OPINION Given the abundant promise found within the mGlu5 NAM field, optimism remains that a drug will emerge from this therapeutic class. Still, the launch of a new drug is far from a certainty. It is encouraging to observe the ever-increasing chemical diversity among mGlu5 NAMs. Finally, in spite of the mature nature of this field, room remains for new advancements.
Collapse
Affiliation(s)
- Kyle A Emmitte
- Vanderbilt University Medical Center, Vanderbilt Center for Neuroscience Drug Discovery, Department of Chemistry, Nashville, TN 37232, USA.
| |
Collapse
|
34
|
Ben-Shahar O, Sacramento AD, Miller BW, Webb SM, Wroten MG, Silva HE, Caruana AL, Gordon EJ, Ploense KL, Ditzhazy J, Kippin TE, Szumlinski KK. Deficits in ventromedial prefrontal cortex group 1 metabotropic glutamate receptor function mediate resistance to extinction during protracted withdrawal from an extensive history of cocaine self-administration. J Neurosci 2013; 33:495-506a. [PMID: 23303930 PMCID: PMC3711633 DOI: 10.1523/jneurosci.3710-12.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/28/2012] [Accepted: 10/21/2012] [Indexed: 11/21/2022] Open
Abstract
Anomalies in prefrontal cortex (PFC) function are posited to underpin difficulties in learning to suppress drug-seeking behavior during abstinence. Because group 1 metabotropic glutamate receptors (mGluRs) regulate drug-related learning, we assayed the consequences of extended access to intravenous cocaine (6 h/d; 0.25 mg/infusion for 10 d) on the PFC expression of group 1 mGluRs and the relevance of observed changes for cocaine seeking. After protracted withdrawal, cocaine-experienced animals exhibited a time-dependent intensification of cue-induced cocaine-seeking behavior and an impaired extinction of this behavior. These behavioral phenomena were associated with a time-dependent reduction in mGluR1/5 expression within ventromedial PFC (vmPFC) of cocaine-experienced animals exposed to extinction testing but not in untested ones. Interestingly, pharmacological manipulations of vmPFC mGluR1/5 produced no immediate effects on cue-induced cocaine-seeking behavior but produced residual effects on a subsequent test for cocaine seeking. At 3 d withdrawal, cocaine-experienced rats infused intra-vmPFC with mGluR1/5 antagonists, either before or after an initial test for cocaine seeking, persisted in their cocaine seeking akin to cocaine-experienced rats in protracted withdrawal. Conversely, cocaine-experienced rats infused with an mGluR1/5 agonist before the initial test for cocaine-seeking at 30 d withdrawal exhibited a facilitation of extinction learning. These data indicate that cue-elicited deficits in vmPFC group 1 mGluR function mediate resistance to extinction during protracted withdrawal from a history of extensive cocaine self-administration and pose pharmacological stimulation of these receptors as a potential approach to facilitate learned suppression of drug-seeking behavior that may aid drug abstinence.
Collapse
Affiliation(s)
- Osnat Ben-Shahar
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Arianne D. Sacramento
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Bailey W. Miller
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Sierra M. Webb
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Melissa G. Wroten
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Hannah E. Silva
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Amanda L. Caruana
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Evan J. Gordon
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Kyle L. Ploense
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Jennifer Ditzhazy
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, California 93106-9660
| |
Collapse
|
35
|
Schwendt M, Sigmon SA, McGinty JF. RGS4 overexpression in the rat dorsal striatum modulates mGluR5- and amphetamine-mediated behavior and signaling. Psychopharmacology (Berl) 2012; 221:621-35. [PMID: 22193724 PMCID: PMC4507824 DOI: 10.1007/s00213-011-2606-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 11/30/2011] [Indexed: 12/14/2022]
Abstract
RATIONALE Regulator of G-protein signaling 4 (RGS4) is a brain-enriched negative modulator of G-protein-coupled receptor signaling. Decreased availability of RGS4 in the frontal cortex and striatum has been described in animal models of schizophrenia and drug addiction. However, cellular and behavioral consequences of dysregulated RGS4-dependent receptor signaling in the brain remain poorly understood. OBJECTIVE This study aims to investigate whether RGS4, through inhibiting the function of mGluR5 receptors in the dorsal striatum (dSTR), regulates cellular and behavioral responses to acute amphetamine. METHODS After herpes simplex virus-RGS4 was infused into the dSTR, RGS4 overexpression as well as binding of recombinant RGS4 to mGluR5 was assessed. The effect of RGS4 overexpression on behavioral activity induced by the intrastriatal mGluR5 agonist, DHPG, or amphetamine was recorded. Activation of extracellular signal-regulated kinase (ERK) and Akt (protein kinase B) was measured in the dSTR tissue at the end of each behavioral experiment. RESULTS RGS4 overexpressed in the dSTR coimmunoprecipitated with mGluR5 receptors and suppressed both behavioral activity and phospho-ERK levels induced by DHPG. RGS4 overexpression or the mGluR5 antagonist, 3-((2-methyl-4-thiazolyl)ethynyl)pyridine (MTEP), attenuated amphetamine-induced phospho-ERK (but not phospho-Akt) levels. RGS4 suppressed amphetamine-induced vertical activity and augmented horizontal activity over 90 min. Similarly, MTEP augmented amphetamine-induced horizontal activity, but did not affect vertical activity. CONCLUSIONS The present data demonstrate that RGS4 in the dSTR attenuates amphetamine-induced ERK signaling and decreases the behavioral efficacy of acute amphetamine likely by limiting mGluR5 function.
Collapse
Affiliation(s)
| | | | - Jacqueline F. McGinty
- Address all correspondence and reprint requests to: Jacqueline McGinty, Ph.D., Department of Neurosciences, Medical University of South Carolina, 173 Ashley Avenue, BSB 403, MSC 510, Charleston, SC 29425-5100, tel 843-792-9036, fax 843-792-4423,
| |
Collapse
|
36
|
mGluR5 receptors in the basolateral amygdala and nucleus accumbens regulate cue-induced reinstatement of ethanol-seeking behavior. Pharmacol Biochem Behav 2012; 101:329-35. [PMID: 22296815 DOI: 10.1016/j.pbb.2012.01.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 01/25/2023]
Abstract
Pharmacological blockade of the type 5 metabotropic glutamate receptor (mGluR5) attenuates cue-induced reinstatement of ethanol-seeking behavior, yet the brain regions involved in these effects are not yet known. The purpose of the present study was to determine if local blockade of mGluR5 receptors in the basolateral amygdala (BLA) and/or the nucleus accumbens (NAc), two brain regions known to be involved in stimulus-reward associations, attenuate the reinstatement of ethanol-seeking behavior induced by ethanol-paired cues. As a control for possible non-specific effects, the effects of mGluR5 blockade in these regions on cue-induced reinstatement of sucrose-seeking were also assessed. Male Wistar rats were implanted with bilateral microinjection cannulae aimed at the BLA or NAc. Following recovery, animals were trained to self-administer ethanol (10% w/v) or 45 mg sucrose pellets on an FR1 schedule of reinforcement in 30 min daily sessions using a sucrose fading procedure. Following stabilization of responding, animals underwent extinction training. Next, animals received infusions of vehicle or the selective mGluR5 antagonist MTEP (3 μg/μl) into the BLA or NAc prior to cue-induced reinstatement testing sessions. mGluR5 blockade eliminated cue-induced reinstatement of alcohol - but not sucrose-seeking behavior. Results from this study indicate that mGluR5 receptors in the BLA and NAc mediate cue-induced reinstatement of ethanol-seeking behavior, and provide two potential neuroanatomical sites of action where systemically administered mGluR5 antagonists attenuate cue-induced reinstatement. These data are consistent with previous findings that cue-induced reinstatement of ethanol-seeking increases neuronal activity and glutamatergic transmission in these two regions.
Collapse
|
37
|
Cleva RM, Olive MF. Metabotropic glutamate receptors and drug addiction. ACTA ACUST UNITED AC 2012; 1:281-295. [DOI: 10.1002/wmts.18] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
38
|
The selective metabotropic glutamate receptor 7 allosteric agonist AMN082 prevents reinstatement of extinguished ethanol-induced conditioned place preference in mice. Pharmacol Biochem Behav 2012; 101:193-200. [PMID: 22269296 DOI: 10.1016/j.pbb.2012.01.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 01/07/2012] [Accepted: 01/09/2012] [Indexed: 11/20/2022]
Abstract
Alcohol dependence is considered a major public health problem in modern societies. The role for glutamatergic neurotransmission in the reinforcing effects of ethanol is becoming increasingly evident. Our previous findings have shown that in rats, the mGluR7 positive allosteric agonist AMN082, but not its allosteric antagonist MMPIP, prevented ethanol consumption and preference in the two-bottle choice paradigm. This study was conducted to determine the effects of AMN082 and MMPIP on the extinction and reinstatement of ethanol-elicited place preference (CPP) in C57BL/6 mice. AMN082 and MMPIP were administered during extinction of ethanol CPP to determine whether mGluR7 signaling is required. Furthermore, the effects of AMN082 and MMPIP on reinstatement of CPP were also evaluated. Finally, spontaneous locomotor activity and ethanol pharmacokinetics were assessed following systemic administration of AMN082 and MMPIP. Our results indicate that mGluR7 pharmacological modulation had no effect on ethanol-elicited CPP extinction. In contrast, mGluR7 activation using AMN082 reduced ethanol-induced CPP reinstatement, an effect reversed by co-administration of MMPIP. Collectively, these results indicate, for the first time, that activation of the mGluR7 receptor is effective in reducing the reinstatement of conditioned rewarding effects of ethanol. Taken together, the efficacy of AMN082 on the various phases of alcohol-CPP could represent an interesting pharmacological approach and could open a new line of research for the development of therapies to reduce ethanol intake in patients.
Collapse
|
39
|
Cleva RM, Watterson LR, Johnson MA, Olive MF. Differential Modulation of Thresholds for Intracranial Self-Stimulation by mGlu5 Positive and Negative Allosteric Modulators: Implications for Effects on Drug Self-Administration. Front Pharmacol 2012; 2:93. [PMID: 22232603 PMCID: PMC3252814 DOI: 10.3389/fphar.2011.00093] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 12/21/2011] [Indexed: 12/20/2022] Open
Abstract
Pharmacological manipulation of the type 5 metabotropic glutamate (mGlu5) receptor alters various addiction related behaviors such as drug self-administration and the extinction and reinstatement of drug-seeking behavior. However, the effects of pharmacological modulation of mGlu5 receptors on brain reward function have not been widely investigated. We examined the effects of acute administration of positive and negative allosteric modulators (PAMs and NAMs, respectively) on brain reward function by assessing thresholds for intracranial self-stimulation (ICSS). In addition, when acute effects were observed, we examined changes in ICSS thresholds following repeated administration. Male Sprague-Dawley rats were implanted with bipolar electrodes into the medial forebrain bundle and trained to respond for ICSS, followed by assessment of effects of mGlu5 ligands on ICSS thresholds using a discrete trials current–intensity threshold determination procedure. Acute administration of the selective mGlu5 NAMs MTEP (0, 0.3, 1, or 3 mg/kg) and fenobam (0, 3, 10, or 30 mg/kg) dose-dependently increased ICSS thresholds (∼70% at the highest dose tested), suggesting a deficit in brain reward function. Acute administration of the mGlu5 PAMs CDPPB (0, 10, 30, and 60 mg/kg) or ADX47273 (0, 10, 30, and 60 mg/kg) was without effect at any dose tested. When administered once daily for five consecutive days, the development of tolerance to the ability of threshold-elevating doses of MTEP and fenobam to increase ICSS thresholds was observed. We conclude that mGlu5 PAMs and NAMs differentially affect brain reward function, and that tolerance to the ability of mGlu5 NAMs to reduce brain reward function develops with repeated administration. These brain reward deficits should be taken into consideration when interpreting acute effects of mGlu5 NAMs on drug self-administration, and repeated administration of these ligands may be an effective method to reduce these deficits.
Collapse
Affiliation(s)
- Richard M Cleva
- Interdisciplinary Graduate Program in Neuroscience, Arizona State University Tempe, AZ, USA
| | | | | | | |
Collapse
|
40
|
Enhanced sensitivity to attenuation of conditioned reinstatement by the mGluR 2/3 agonist LY379268 and increased functional activity of mGluR 2/3 in rats with a history of ethanol dependence. Neuropsychopharmacology 2011; 36:2762-73. [PMID: 21881571 PMCID: PMC3230501 DOI: 10.1038/npp.2011.174] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent findings implicate group II metabotropic glutamate receptors (mGluR(2/3)) in the reinforcing and dependence-inducing actions of ethanol and identify these receptors as treatment targets for alcoholism. Here, we investigated the effects of mGLuR(2/3) activation on conditioned reinstatement in rats with different ethanol-dependence histories and examined dependence-associated changes in the functional activity of mGluR(2/3). Following ethanol self-administration training and conditioning procedures, rats were made ethanol dependent, using ethanol vapor inhalation, under three conditions: a single intoxication and withdrawal episode (SW), repeated cycles of intoxication and withdrawal (RW), or no intoxication (CTRL). At 1 week after removal from ethanol vapor, self-administration resumed until stable baseline performance was reached, followed by extinction of operant responding and reinstatement tests. Post-withdrawal self-administration was increased in the RW group, but all groups showed conditioned reinstatement. The mGluR(2/3) agonist LY379268 dose -dependently reduced reinstatement in all groups, but was more effective at low doses in the SW and RW groups. The highest dose of LY379268 tested reduced spontaneous locomotor activity and operant responding maintained by a non-drug reinforcer, without differences among groups. The heightened sensitivity to the effects of LY379268 in rats with an ethanol-dependence history was therefore specific to behavior motivated by ethanol-related stimuli. Both the SW and RW groups showed elevated [(35)S]GTPγS binding in the central nucleus of the amygdala (CeA) and bed nucleus of stria terminalis (BNST), relative to the CTRL group. The findings implicate changes in mGluR(2/3) functional activity as a factor in ethanol dependence and support treatment target potential of mGlu(2/3) receptors for craving and relapse prevention.
Collapse
|
41
|
Kotlinska JH, Bochenski M, Danysz W. The role of group I mGlu receptors in the expression of ethanol-induced conditioned place preference and ethanol withdrawal seizures in rats. Eur J Pharmacol 2011; 670:154-61. [DOI: 10.1016/j.ejphar.2011.09.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 09/02/2011] [Accepted: 09/11/2011] [Indexed: 11/27/2022]
|
42
|
Eiler WJA, Baez M, Yu J, Witkin JM. mGlu5 receptor deletion reduces relapse to food-seeking and prevents the anti-relapse effects of mGlu5 receptor blockade in mice. Life Sci 2011; 89:862-7. [PMID: 21983299 DOI: 10.1016/j.lfs.2011.09.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 07/15/2011] [Accepted: 09/10/2011] [Indexed: 12/21/2022]
Abstract
AIMS Convergent data suggest that there is a hyperglutamatergic state that arises during relapse to drug seeking. Blockade of mGlu5 receptors provides one approach to dampening glutamate tone. However, the role of mGlu5 receptors in relapse to food seeking behavior has not been explored extensively and has not been scrutinized using receptor null mice. MAIN METHODS Wild-type (WT) and mGlu5 receptor knockout (KO) mice were compared under the acquisition of a discriminated operant response maintained by food, during extinction of the response, and during the reinstatement of the response by food and food-associated stimuli. The impact of the mGlu5 receptor antagonist MTEP was investigated. KEY FINDINGS Acquisition and extinction were not markedly different in WT and KO mice. MTEP decreased response reinstatement in WT mice. This behavioral effect of MTEP was not present in the KO mice, demonstrating the dependence of the effect of MTEP on mGlu5 receptors. As with the effect of MTEP in WT mice, receptor deletion reduced response reinstatement in KO mice. SIGNIFICANCE This is the first report to evaluate the reinstatement of food-seeking in mGlu5 receptor KO mice. The data reported here add to those in the literature that support a role for mGlu5 receptors in the control of this relapse effect. The data also reinforce the potential utility of mGlu5 receptor antagonists in relapse prevention to food-seeking behaviors.
Collapse
Affiliation(s)
- William J A Eiler
- Neuroscience Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285-0510, USA
| | | | | | | |
Collapse
|
43
|
Metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) microinfusions into the nucleus accumbens shell or ventral tegmental area attenuate the reinforcing effects of nicotine in rats. Neuropharmacology 2011; 61:1399-405. [PMID: 21896278 DOI: 10.1016/j.neuropharm.2011.08.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 08/03/2011] [Accepted: 08/19/2011] [Indexed: 12/13/2022]
Abstract
Systemic administration of the mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) was previously shown to selectively attenuate nicotine self-administration without affecting food-maintained responding in rats. Glutamatergic neurotransmission in the ventral tegmental area (VTA) and nucleus accumbens (NAcc) shell plays an important role in the reinforcing effects of nicotine. To determine the brain sites that may mediate the systemic effects of MPEP on nicotine self-administration, the present study investigated the effects of MPEP microinfusions into the VTA or the NAcc shell on nicotine and food self-administration in separate groups of rats. Administration of low MPEP doses (0, 0.5, 1, and 2 μg/0.5 μl/side) microinfused into the NAcc shell had no effect on nicotine self-administration, whereas higher MPEP doses (0, 10, 20, and 40 μg/0.5 μl/side) microinfused into the NAcc shell dose-dependently attenuated nicotine self-administration without affecting food-maintained responding. Microinfusions of MPEP into the VTA (0, 10, 20, and 40 μg/0.5 μl/side) significantly decreased both nicotine and food self-administration at 20 μg/0.5 μl/side but did not affect responding for either reinforcer at 40μg/0.5 μl/side. This lack of effect of 40 μg/0.5 μl/side MPEP on either nicotine or food self-administration when administered into the VTA may be attributable either to actions of MPEP at presynaptic mGlu5 receptors or at targets other than mGlu5 receptors. Importantly, anatomical control injections 2mm above the NAcc shell or the VTA using the most effective MPEP dose in the two regions did not result in attenuation of nicotine self-administration. In conclusion, MPEP microinfusions in the VTA or NAcc shell attenuates the reinforcing effects of nicotine possibly via blockade of mGlu5 receptors located in these regions.
Collapse
|
44
|
Emmitte KA. Recent advances in the design and development of novel negative allosteric modulators of mGlu(5). ACS Chem Neurosci 2011; 2:411-432. [PMID: 21927649 DOI: 10.1021/cn2000266] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Negative allosteric modulators (NAMs) of metabotropic glutamate receptor subtype 5 (mGlu(5)) have remained attractive to researchers as potential therapies for a number of central nervous system related diseases, including anxiety, pain, gastroesophageal reflux disease (GERD), addiction, Parkinson's disease (PD), and fragile X syndrome (FXS). In addition to the many publications with supportive preclinical data with key tool molecules, recent positive reports from the clinic have bolstered the confidence in this approach. During the two year time span from 2009 through 2010, a number of new mGlu(5) NAM chemotypes have been disclosed and discussed in the primary and patent literature. A summary of several efforts representing many diverse chemotypes are presented here, along with a discussion of representative structure activity relationships (SAR) and synthetic approaches to the templates where possible.
Collapse
Affiliation(s)
- Kyle A. Emmitte
- Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, and Department of Chemistry, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| |
Collapse
|
45
|
Carrara-Nascimento PF, Griffin WC, Pastrello DM, Olive MF, Camarini R. Changes in extracellular levels of glutamate in the nucleus accumbens after ethanol-induced behavioral sensitization in adolescent and adult mice. Alcohol 2011; 45:451-60. [PMID: 21570797 DOI: 10.1016/j.alcohol.2011.01.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 01/20/2011] [Accepted: 01/24/2011] [Indexed: 12/25/2022]
Abstract
Repeated administration of low doses of ethanol gradually increases locomotor responses to ethanol in adult Swiss mice. This phenomenon is known as behavioral sensitization. However, we have shown that adolescent Swiss mice show either behavioral tolerance or no sensitization after repeated ethanol injections. Although the mesolimbic dopamine system has been extensively implicated in behavioral sensitization, several studies have demonstrated an important role of glutamatergic transmission in this phenomenon. In addition, relatively few studies have examined the role of developmental factors in behavioral sensitization to ethanol. To examine the relationship between age differences in behavioral sensitization to ethanol and the neurochemical adaptations related to glutamate within nucleus accumbens (NAc), in vivo microdialysis was conducted in adolescent and adult Swiss mice treated with ethanol (1.8 g/kg) or saline for 15 days and subsequently challenged with an acute dose (1.8 g/kg) of ethanol 6 days later. Consistent with previous findings, only adult mice demonstrated evidence of behavioral sensitization. However, ethanol-treated adolescent mice demonstrated a 196.1 ± 40.0% peak increase in extracellular levels of glutamate in the NAc after ethanol challenge in comparison with the basal values, whereas ethanol-treated adult mice demonstrated a 52.2 ± 6.2% reduction in extracellular levels of glutamate in the NAc after ethanol challenge. These observations suggest an age-dependent inverse relationship between behavioral and glutamatergic responses to repeated ethanol exposure.
Collapse
|
46
|
Bahi A. Retracted article: Selective activation of the metabotropic glutamate receptor subtype 7 "mGluR7" attenuates acquisition, expression, and reinstatement of ethanol place preference. Psychopharmacology (Berl) 2011; 216:601. [PMID: 21706135 DOI: 10.1007/s00213-011-2371-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/24/2011] [Indexed: 10/18/2022]
Affiliation(s)
- Amine Bahi
- Faculty of Medicine and Health Sciences, Department of Anatomy, United Arab Emirates University, Al Ain, United Arab Emirates.
| |
Collapse
|
47
|
Rutten K, Van Der Kam EL, De Vry J, Bruckmann W, Tzschentke TM. The mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) potentiates conditioned place preference induced by various addictive and non-addictive drugs in rats. Addict Biol 2011; 16:108-15. [PMID: 20579001 DOI: 10.1111/j.1369-1600.2010.00235.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We have recently reported that the metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) potentiates acquisition of conditioned place preference (CPP) induced by heroin and ketamine. The present study investigated to what extent this effect of MPEP can be generalized to other classes of drugs, such as the stimulants nicotine and cocaine, and to drugs that produce CPP in the rat despite a lack of abuse potential in humans, such as buspirone and clonidine. Adult male Sprague Dawley rats were subjected to a standard unbiased CPP protocol (six conditioning sessions lasting 20 minutes for nicotine and 40 minutes for the other compounds). Rats were conditioned with either nicotine (0.05-0.2 mg/kg, subcutaneously), cocaine [1-10 mg/kg, intraperitoneally (i.p.)], buspirone (0.3-3 mg/kg, i.p.) or clonidine (0.2-0.6 mg/kg, i.p.) in combination with MPEP (0 or 10 mg/kg, i.p.). For nicotine and cocaine, the minimal effective dose to induce CPP was lowered by pre-treatment with MPEP. While buspirone and clonidine did not induce CPP when given alone (i.e. combined with MPEP vehicle), both compounds induced CPP after pre-treatment with MPEP. It is concluded that MPEP consistently potentiates acquisition of drug-induced reward, independent of the mechanism of action of the co-administered drug. We suggest that the proposed anti-abuse effect of MPEP may be due to a substitution-like effect.
Collapse
Affiliation(s)
- Kris Rutten
- Department of Pharmacology, Aachen, Germany.
| | | | | | | | | |
Collapse
|
48
|
Protein kinase C isozymes as regulators of sensitivity to and self-administration of drugs of abuse-studies with genetically modified mice. Behav Pharmacol 2010; 21:493-9. [PMID: 20671547 DOI: 10.1097/fbp.0b013e32833d8bb7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Studies using targeted gene deletion in mice have revealed distinct roles for individual isozymes of the protein kinase C (PKC) family of enzymes in regulating sensitivity to various drugs of abuse. These changes in drug sensitivity are associated with altered patterns of drug self-administration. The purpose of this review is to summarize behavioral studies conducted on mice carrying targeted deletions of genes encoding specific PKC isozymes (namely the beta, gamma, delta, and epsilon isozymes), and to critically evaluate the possibility of using pharmacological inhibitors of specific PKC isozymes as modulators of the sensitivity to various drugs of abuse, as well as potential aids in the treatment of substance use disorders.
Collapse
|
49
|
Hao Y, Martin-Fardon R, Weiss F. Behavioral and functional evidence of metabotropic glutamate receptor 2/3 and metabotropic glutamate receptor 5 dysregulation in cocaine-escalated rats: factor in the transition to dependence. Biol Psychiatry 2010; 68:240-8. [PMID: 20416862 PMCID: PMC2907426 DOI: 10.1016/j.biopsych.2010.02.011] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/11/2010] [Accepted: 02/12/2010] [Indexed: 10/25/2022]
Abstract
BACKGROUND Rats with extended daily cocaine access show escalating cocaine self-administration and behavioral signs of dependence. Regulation of glutamatergic transmission by metabotropic glutamate receptors has emerged as a mechanism in the addictive actions of drugs of abuse. We examined here whether neuroadaptive dysregulation of metabotropic glutamate receptor function is a factor in escalating cocaine self-administration. METHODS Rats with 1 hour daily cocaine access (short access [ShA]) versus 6-hour access (long access [LgA]) were tested for differences in the effects of the metabotropic glutamate receptor 2/3 (mGluR2/3) agonist (-)-2-oxa-4-aminobicylco(3.1.0)hexane-4,6-dicarboxylic acid (LY379268) and the metabotropic glutamate receptor 5 (mGluR5) antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP) on cocaine-reinforced progressive-ratio responding and differences in expression levels and functional activity of mGluR2/3 and mGluR5. RESULTS The LgA groups showed higher progressive-ratio breakpoints than ShA groups. LY379268 (0-3 mg/kg subcutaneous) dose-dependently lowered breakpoints in the LgA group but reduced breakpoints only at 3 mg/kg in the ShA group. Consistent with this behavioral effect, functional mGluR2/3 activity was significantly elevated following LgA cocaine exposure. MTEP (0-3 mg/kg intraperitoneal) reduced breakpoints in the ShA group only. Long access cocaine exposure was associated with decreased mGluR5 expression, accompanied by reduced functional mGluR5 activity in the nucleus accumbens. A downward trend developed in mGluR5 protein expression in the medial prefrontal cortex and hippocampus. CONCLUSIONS Functional upregulation of mGluR2/3 and downregulation of mGluR5 are likely factors in the transition to cocaine dependence. The differential behavioral effects of LY379268 and MTEP in rats with a history of long access to cocaine have implications for the treatment target potential of mGluR2/3 and mGluR5.
Collapse
Affiliation(s)
- Yue Hao
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California, USA.
| | | | | |
Collapse
|
50
|
Olive MF. Cognitive effects of Group I metabotropic glutamate receptor ligands in the context of drug addiction. Eur J Pharmacol 2010; 639:47-58. [PMID: 20371237 DOI: 10.1016/j.ejphar.2010.01.029] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 01/14/2010] [Accepted: 01/20/2010] [Indexed: 01/03/2023]
Abstract
Glutamate plays a pivotal role in regulating drug self-administration and drug-seeking behavior, and the past decade has witnessed a substantial surge of interest in the role of Group I metabotropic glutamate receptors (mGlu(1) and mGlu(5) receptors) in mediating these behaviors. As will be reviewed here, Group I mGlu receptors are involved in normal and drug-induced synaptic plasticity, drug reward, reinforcement and relapse-like behaviors, and addiction-related cognitive processes such as maladaptive learning and memory, behavioral inflexibility, and extinction learning. Animal models of addiction have revealed that antagonists of Group I mGlu receptors, particularly the mGlu(5) receptor, reduce self-administration of virtually all drugs of abuse. Since inhibitors of mGlu5 receptor function have now entered clinical trials for other medical conditions and appear to be well-tolerated, a key question that remains unanswered is - what changes in cognition are produced by these compounds that result in reduced drug intake and drug-seeking behavior? Finally, in contrast to mGlu(5) receptor antagonists, recent studies have indicated that positive allosteric modulation of mGlu(5) receptors actually enhances synaptic plasticity and improves various aspects of cognition, including spatial learning, behavioral flexibility, and extinction of drug-seeking behavior. Thus, while inhibition of Group I mGlu receptor function may reduce drug reward, reinforcement, and relapse-related behaviors, positive allosteric modulation of the mGlu5 receptor subtype may actually enhance cognition and potentially reverse some of the cognitive deficits associated with chronic drug use.
Collapse
Affiliation(s)
- M Foster Olive
- Center for Drug and Alcohol Programs, Department of Psychiatry, Medical University of South Carolina, 67 President Street, MSC 861, Charleston, SC 29425, USA.
| |
Collapse
|