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Pardo-García TR, Yusif-Rodriguez N, Yudowski G, Maldonado-Vlaar CS. Blockade of the endovanilloid receptor, TRPV1, and of the endocannabinoid enzyme, FAAH, within the nucleus accumbens shell elicits anxiolytic-like effects in male rats. Neurosci Lett 2020; 732:135023. [PMID: 32422166 DOI: 10.1016/j.neulet.2020.135023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/15/2020] [Accepted: 04/28/2020] [Indexed: 11/17/2022]
Abstract
RATIONALE The functional role of the endocannabinoid system (ECS) and Transient Receptor Potential Vanilloid type-1 (TRPV1) within the Nucleus Accumbens shell (NAc shell) remains unknown. Preclinical studies in rodents have reported that the ECS modulates emotional responses such as anxiety. The NAc shell has a high density of synaptically co-localized cannabinoid receptor type-1 (CB1R) and TRPV1, suggesting a potential involvement in the modulation of anxiety. OBJECTIVES The present study aims to establish the role of ECS-TRPV1 interactions within the NAc shell and its effects on anxiety. It is hypothesized that the neurochemical regulation elicited by ECS within the NAc shell mediates anxiety-like behaviors in rodents. METHODS In this study, male Sprague Dawley rats were implanted with bilateral brain cannula targeting the NAc shell. Following recovery from surgery, animals received microinfusion pretreatments (0, 0.125, 0.5 nmol/0.4 μl) of N-arachidonoyl-serotonin (AA-5-HT), a dual blocker of the endocannabinoid-inactivating enzyme, fatty acid amide hydrolase (FAAH) and a TRPV1 antagonist in the NAc shell. Following treatment, animals were tested in an elevated plus maze (EPM) paradigm for a period of 5 minutes. At the end of the experiment, animals were sacrificed and their brains collected for histological and biochemical analysis. RESULTS Results showed that animals treated with AA-5-HT in a dose dependent manner spent significantly more time in the open arms than vehicle-treated animals. In addition, AA-5-HT administration induced a significant downregulation of CB1R expression in the NAc shell. CONCLUSIONS The present findings suggest that the ECS within the NAc shell modulates anxiety-like behaviors via FAAH and CB1R activity.
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Affiliation(s)
- Thibaut R Pardo-García
- University of Puerto Rico-Rio Piedras Campus, Department of Biology, PO Box 23360, San Juan, 00931, Puerto Rico.
| | - Nadira Yusif-Rodriguez
- University of Puerto Rico-Rio Piedras Campus, Department of Biology, PO Box 23360, San Juan, 00931, Puerto Rico.
| | - Guillermo Yudowski
- University of Puerto Rico-Medical School, Institute of Neurobiology, San Juan, 00936, Puerto Rico
| | - Carmen S Maldonado-Vlaar
- University of Puerto Rico-Rio Piedras Campus, Department of Biology, PO Box 23360, San Juan, 00931, Puerto Rico.
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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.
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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.
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3
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Mao LM, Wang JQ. Amphetamine-induced Conditioned Place Preference and Changes in mGlu1/5 Receptor Expression and Signaling in the Rat Medial Prefrontal Cortex. Neuroscience 2018; 400:110-119. [PMID: 30599269 DOI: 10.1016/j.neuroscience.2018.12.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/27/2018] [Accepted: 12/21/2018] [Indexed: 12/27/2022]
Abstract
The medial prefrontal cortex (mPFC) is implicated in the rewarding effect of psychostimulants, although molecular mechanisms underlying the rewarding properties of stimulants in this region are poorly understood. Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are believed to be critical in this event. We thus in this study investigated changes in mGlu1/5 receptor expression and function in the rat mPFC in response to conditioned place preference (CPP) induced by amphetamine. Repeated amphetamine administration (2.5 mg/kg, once daily on alternate days for 10 days) induced reliable CPP. In the mPFC, surface expression of mGlu5 receptors was elevated in rats after amphetamine conditioning. mGlu5 receptors were also increased at synaptic and extrasynaptic sites in amphetamine-conditioned rats. Expression of mGlu1 receptors was stable in surface and synaptic compartments, while it was elevated in the extrasynaptic location. In mPFC neurons, the mGlu1/5 agonist-stimulated phosphoinositide signaling pathway was upregulated in its efficacy following amphetamine conditioning. The mGlu1/5 agonist-stimulated Src kinase phosphorylation was also augmented in rats treated with amphetamine. These results demonstrate the sensitivity of mPFC mGlu1/5 receptors to amphetamine-induced CPP. Amphetamine conditioning results in the upregulation of mGlu1/5 receptor expression at subcellular and/or subsynaptic levels and mGlu1/5-mediated postreceptor signaling in mPFC neurons.
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Affiliation(s)
- Li-Min Mao
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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Gupta I, Young AMJ. Metabotropic glutamate receptor modulation of dopamine release in the nucleus accumbens shell is unaffected by phencyclidine pretreatment: In vitro assessment using fast-scan cyclic voltammetry rat brain slices. Brain Res 2018. [PMID: 29524437 DOI: 10.1016/j.brainres.2018.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The non-competitive glutamate antagonist, phencyclidine is used in rodents to model behavioural deficits see in schizophrenia. Importantly, these deficits endure long after the cessation of short-term chronic treatment (sub-chronic), indicating that the drug treatment causes long-term changes in the physiology and/or chemistry of the brain. There is evidence that this may occur through glutamatergic modulation of mesolimbic dopamine release, perhaps involving metabotropic glutamate receptors (mGluR). This study sought to investigate the effect of sub-chronic phencyclidine pretreatment on modulation of dopamine neurotransmission by metabotropic glutamate receptors 2 and 5 (mGluR2 and mGluR5) in the nucleus accumbens shell in vitro, with the hypothesis that phencyclidine pretreatment would disrupt the mGluR-mediated modulation of dopamine release. We showed that the orthosteric mGluR2 agonist LY379268 (0.1 µM, 1 µM and 10 µM) and mGluR5 positive allosteric modulator CDPPB (1 µM and 10 µM) both attenuated potassium-evoked dopamine release, underscoring their role in modulating dopamine neurotransmission in the nucleus accumbens. Sub-chronic PCP treatment, which caused cognitive deficits measured by performance in the novel object recognition task, modelling aspects of behavioral deficits seen in schizophrenia, induced neurobiological changes that enhanced dopamine release in the nucleus accumbens, but had no effect on mGluR2 or mGluR5 mediated changes in dopamine release. Therefore it is unlikely that schizophrenia-related behavioural changes seen after sub-chronic phencyclidine pre-treatment are mediated through mGluR modulation of dopamine release.
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Affiliation(s)
- Ishan Gupta
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Andrew M J Young
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
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Li X, Peng XQ, Jordan CJ, Li J, Bi GH, He Y, Yang HJ, Zhang HY, Gardner EL, Xi ZX. mGluR5 antagonism inhibits cocaine reinforcement and relapse by elevation of extracellular glutamate in the nucleus accumbens via a CB1 receptor mechanism. Sci Rep 2018; 8:3686. [PMID: 29487381 PMCID: PMC5829076 DOI: 10.1038/s41598-018-22087-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 02/16/2018] [Indexed: 12/02/2022] Open
Abstract
Metabotropic glutamate receptor 5 (mGluR5) antagonism inhibits cocaine self-administration and reinstatement of drug-seeking behavior. However, the cellular and molecular mechanisms underlying this action are poorly understood. Here we report a presynaptic glutamate/cannabinoid mechanism that may underlie this action. Systemic or intra-nucleus accumbens (NAc) administration of the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) dose-dependently reduced cocaine (and sucrose) self-administration and cocaine-induced reinstatement of drug-seeking behavior. The reduction in cocaine-taking and cocaine-seeking was associated with a reduction in cocaine-enhanced extracellular glutamate, but not cocaine-enhanced extracellular dopamine (DA) in the NAc. MPEP alone, when administered systemically or locally into the NAc, elevated extracellular glutamate, but not DA. Similarly, the cannabinoid CB1 receptor antagonist, rimonabant, elevated NAc glutamate, not DA. mGluR5s were found mainly in striatal medium-spiny neurons, not in astrocytes, and MPEP-enhanced extracellular glutamate was blocked by a NAc CB1 receptor antagonist or N-type Ca++ channel blocker, suggesting that a retrograde endocannabinoid-signaling mechanism underlies MPEP-induced glutamate release. This interpretation was further supported by our findings that genetic deletion of CB1 receptors in CB1-knockout mice blocked both MPEP-enhanced extracellular glutamate and MPEP-induced reductions in cocaine self-administration. Together, these results indicate that the therapeutic anti-cocaine effects of mGluR5 antagonists are mediated by elevation of extracellular glutamate in the NAc via an endocannabinoid-CB1 receptor disinhibition mechanism.
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Affiliation(s)
- Xia Li
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA. .,Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA.
| | - Xiao-Qing Peng
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA.,Psychiatry Residency Training Program, Department of Behavioral Health, Saint Elizabeths Hospital, 1100 Alabama Ave. SE, Washington, DC, 20032, USA
| | - Chloe J Jordan
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Jie Li
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.,Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Guo-Hua Bi
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Yi He
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Hong-Ju Yang
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Hai-Ying Zhang
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Eliot L Gardner
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Zheng-Xiong Xi
- Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA.
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Scofield MD, Heinsbroek JA, Gipson CD, Kupchik YM, Spencer S, Smith ACW, Roberts-Wolfe D, Kalivas PW. The Nucleus Accumbens: Mechanisms of Addiction across Drug Classes Reflect the Importance of Glutamate Homeostasis. Pharmacol Rev 2017; 68:816-71. [PMID: 27363441 DOI: 10.1124/pr.116.012484] [Citation(s) in RCA: 358] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The nucleus accumbens is a major input structure of the basal ganglia and integrates information from cortical and limbic structures to mediate goal-directed behaviors. Chronic exposure to several classes of drugs of abuse disrupts plasticity in this region, allowing drug-associated cues to engender a pathologic motivation for drug seeking. A number of alterations in glutamatergic transmission occur within the nucleus accumbens after withdrawal from chronic drug exposure. These drug-induced neuroadaptations serve as the molecular basis for relapse vulnerability. In this review, we focus on the role that glutamate signal transduction in the nucleus accumbens plays in addiction-related behaviors. First, we explore the nucleus accumbens, including the cell types and neuronal populations present as well as afferent and efferent connections. Next we discuss rodent models of addiction and assess the viability of these models for testing candidate pharmacotherapies for the prevention of relapse. Then we provide a review of the literature describing how synaptic plasticity in the accumbens is altered after exposure to drugs of abuse and withdrawal and also how pharmacological manipulation of glutamate systems in the accumbens can inhibit drug seeking in the laboratory setting. Finally, we examine results from clinical trials in which pharmacotherapies designed to manipulate glutamate systems have been effective in treating relapse in human patients. Further elucidation of how drugs of abuse alter glutamatergic plasticity within the accumbens will be necessary for the development of new therapeutics for the treatment of addiction across all classes of addictive substances.
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Affiliation(s)
- M D Scofield
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - J A Heinsbroek
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - C D Gipson
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - Y M Kupchik
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - S Spencer
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - A C W Smith
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - D Roberts-Wolfe
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
| | - P W Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina (M.D.S., J.A.H., S.S., D.R.-W., P.W.K.); Department of Psychology, Arizona State University, Tempe, Arizona (C.D.G.); Department of Neuroscience, Hebrew University, Jerusalem, Israel (Y.M.K.); and Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York (A.C.W.S.)
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Guimaraes IM, Carvalho TG, Ferguson SS, Pereira GS, Ribeiro FM. The metabotropic glutamate receptor 5 role on motor behavior involves specific neural substrates. Mol Brain 2015; 8:24. [PMID: 25885370 PMCID: PMC4397819 DOI: 10.1186/s13041-015-0113-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/24/2015] [Indexed: 11/22/2022] Open
Abstract
Background The metabotropic glutamate receptor 5 (mGluR5) is involved in various brain functions, including memory, cognition and motor behavior. Regarding locomotor activity, we and others have demonstrated that pharmacological antagonism of mGluR5 promotes hyperkinesia in mice. Moreover, increased locomotor activity can also be observed in mice following the genetic deletion of mGluR5. However, it is still unclear which specific brain substrates contribute to mGluR5-mediated regulation of motor function. Results Thus, to better understand the role of mGluR5 in motor control and to determine which neural substrates are involved in this regulation we performed stereotactic microinfusions of the mGluR5 antagonist, MPEP, into specific brain regions and submitted mice to the open field and rotarod apparatus. Our findings indicate that mGluR5 blockage elicits distinct outcomes in terms of locomotor activity and motor coordination depending on the brain region injected with mGluR5 antagonist. MPEP injection into either the dorsal striatum or dorsal hippocampus resulted in increased locomotor activity, whereas MPEP injection into either the ventral striatum or motor cortex resulted in hypokinesia. Moreover, MPEP injected into the olfactory bulb increased the distance mice traveled in the center of the open field arena. With respect to motor coordination on the rotarod, injection of MPEP into the motor cortex and olfactory bulb elicited decreased latency to fall. Conclusions Taken together, our data suggest that not only primarily motor neural substrates, but also limbic and sensory structures are involved in mGluR5-mediated motor behavior. Electronic supplementary material The online version of this article (doi:10.1186/s13041-015-0113-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Isabella M Guimaraes
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
| | - Toniana G Carvalho
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
| | - Stephen Sg Ferguson
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute, University of Western Ontario, London, Ontario, N6A 5 K8, Canada.
| | - Grace S Pereira
- Nucleo de Neurociencias, Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
| | - Fabiola M Ribeiro
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
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Anxiolytic effects of oxytocin in cue-induced cocaine seeking behavior in rats. Psychopharmacology (Berl) 2014; 231:4145-55. [PMID: 24760374 DOI: 10.1007/s00213-014-3553-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 03/20/2014] [Indexed: 11/27/2022]
Abstract
RATIONALE Oxytocin (OT) is a neuropeptide previously related to reward, learning, memory, and stress, events associated with cocaine addiction. OT has shown anxiolytic properties in different animal models of anxiety. Moreover, previous data have demonstrated an increase in mRNA OT levels within the nucleus accumbens (NAc) following acute and chronic cocaine exposure in rats. Therefore, OT might play a modulatory role in the rewarding properties of cocaine. OBJECTIVES The present set of experiments aims to examine the role of OT on environmentally elicited cocaine-seeking behavior and whether OT could reduce anxiety associated with this behavior. METHODS Separate groups of rats were trained in a cue-elicited cocaine-seeking behavior paradigm. Prior to the reinstatement phase, animals received microinfusions of artificial cerebrospinal fluid (aCSF), OT, OT agonist (TgOT), or OT antagonist (OTA) within the intracerebral ventricular intracerebroventricular (ICV) system. To test OT anxiolytic effects in reinstatement behavior, separate groups of animals were trained in a cue-elicited cocaine-seeking behavior protocol or in a cocaine-conditioning paradigm. At the end of each behavioral training, all animals were ICV pretreated with aCSF or OT, and then exposed to an elevated plus maze. RESULTS Results showed that OT and TgOT pretreatment significantly reduced reinstatement of cocaine-seeking behavior. Most significantly, OT treatment reduced the anxiety triggered by cue-induced reinstatement conditions and cocaine-paired conditioned locomotion. CONCLUSIONS The present study demonstrates for the first time that OT actions within the brain mediate the anxiety response triggered by cues previously paired with cocaine intake.
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Bird MK, Lohmann P, West B, Brown RM, Kirchhoff J, Raymond CR, Lawrence AJ. The mGlu5 receptor regulates extinction of cocaine-driven behaviours. Drug Alcohol Depend 2014; 137:83-9. [PMID: 24576814 DOI: 10.1016/j.drugalcdep.2014.01.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/07/2014] [Accepted: 01/13/2014] [Indexed: 11/24/2022]
Abstract
BACKGROUND There is extensive evidence implicating the metabotropic glutamate 5 (mGlu5) receptor in aspects of addiction-related behaviours. METHODS Here, we used a well-characterized line of mGlu5-deficient mice to further examine the role of this receptor in cocaine-driven behaviours. We confirmed the previously reported deficit in hippocampal long-term potentiation and associated spatial learning impairment. RESULTS Despite a spatial learning deficit, mGlu5-deficient mice developed and maintained a conditioned place preference to cocaine, suggesting cocaine reward and Pavlovian conditioning are intact in these animals. Notably, however, mGlu5-deficient mice exhibited a marked deficit in the extinction of a cocaine-conditioned place preference compared to wild type littermates. Moreover, in a fixed ratio operant intravenous self-administration paradigm, both genotypes showed similar responding for cocaine over two different doses, while mGlu5-deficient mice displayed enhanced responding on a progressive ratio schedule. In addition, cue-induced drug-seeking after abstinence was exaggerated in mGlu5-deficient mice. CONCLUSION Collectively, these findings suggest that while the mGlu5 receptor may be involved in mediating the rewarding effects of cocaine, it appears necessary for the extinction of cocaine-driven behaviours.
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Affiliation(s)
- Michael K Bird
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia
| | - Peter Lohmann
- The John Curtin School of Medical Research & Eccles Institute of Neuroscience, Australian National University, Canberra, Australia
| | - Billy West
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia
| | - Robyn M Brown
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia; Medical University of South Carolina, Charleston, SC, USA
| | - Jeppe Kirchhoff
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia
| | - Clarke R Raymond
- The John Curtin School of Medical Research & Eccles Institute of Neuroscience, Australian National University, Canberra, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia.
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