1
|
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
|
2
|
Holter KM, Pierce BE, Gould RW. Metabotropic glutamate receptor function and regulation of sleep-wake cycles. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:93-175. [PMID: 36868636 DOI: 10.1016/bs.irn.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Metabotropic glutamate (mGlu) receptors are the most abundant family of G-protein coupled receptors and are widely expressed throughout the central nervous system (CNS). Alterations in glutamate homeostasis, including dysregulations in mGlu receptor function, have been indicated as key contributors to multiple CNS disorders. Fluctuations in mGlu receptor expression and function also occur across diurnal sleep-wake cycles. Sleep disturbances including insomnia are frequently comorbid with neuropsychiatric, neurodevelopmental, and neurodegenerative conditions. These often precede behavioral symptoms and/or correlate with symptom severity and relapse. Chronic sleep disturbances may also be a consequence of primary symptom progression and can exacerbate neurodegeneration in disorders including Alzheimer's disease (AD). Thus, there is a bidirectional relationship between sleep disturbances and CNS disorders; disrupted sleep may serve as both a cause and a consequence of the disorder. Importantly, comorbid sleep disturbances are rarely a direct target of primary pharmacological treatments for neuropsychiatric disorders even though improving sleep can positively impact other symptom clusters. This chapter details known roles of mGlu receptor subtypes in both sleep-wake regulation and CNS disorders focusing on schizophrenia, major depressive disorder, post-traumatic stress disorder, AD, and substance use disorder (cocaine and opioid). In this chapter, preclinical electrophysiological, genetic, and pharmacological studies are described, and, when possible, human genetic, imaging, and post-mortem studies are also discussed. In addition to reviewing the important relationships between sleep, mGlu receptors, and CNS disorders, this chapter highlights the development of selective mGlu receptor ligands that hold promise for improving both primary symptoms and sleep disturbances.
Collapse
Affiliation(s)
- Kimberly M Holter
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Bethany E Pierce
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Robert W Gould
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States.
| |
Collapse
|
3
|
Heinsbroek JA, De Vries TJ, Peters J. Glutamatergic Systems and Memory Mechanisms Underlying Opioid Addiction. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a039602. [PMID: 32341068 DOI: 10.1101/cshperspect.a039602] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Glutamate is the main excitatory neurotransmitter in the brain and is of critical importance for the synaptic and circuit mechanisms that underlie opioid addiction. Opioid memories formed over the course of repeated drug use and withdrawal can become powerful stimuli that trigger craving and relapse, and glutamatergic neurotransmission is essential for the formation and maintenance of these memories. In this review, we discuss the mechanisms by which glutamate, dopamine, and opioid signaling interact to mediate the primary rewarding effects of opioids, and cover the glutamatergic systems and circuits that mediate the expression, extinction, and reinstatement of opioid seeking over the course of opioid addiction.
Collapse
Affiliation(s)
- Jasper A Heinsbroek
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Taco J De Vries
- Amsterdam Neuroscience, Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Faculty of Earth and Life Sciences, VU University, 1081HV Amsterdam, The Netherlands.,Amsterdam Neuroscience, Department of Anatomy and Neurosciences, VU University Medical Center, 1081HZ Amsterdam, The Netherlands
| | - Jamie Peters
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| |
Collapse
|
4
|
Abstract
Opioid use disorder (OUD) represents a major public health problem that affects millions of people in the USA and worldwide. The relapsing and recurring aspect of OUD, driven by lasting neurobiological adaptations at different reward centres in the brain, represents a major obstacle towards successful long-term remission from opioid use. Currently, three drugs that modulate the function of the opioidergic receptors, methadone, buprenorphine and naltrexone have been approved by the US Food and Drug Administration (FDA) to treat OUD. In this review, we discuss the limitations and challenges associated with the current maintenance and medication-assisted withdrawal strategies commonly used to treat OUD. We further explore the involvement of glutamatergic, endocannabinoid and orexin signaling systems in the development, maintenance and expression of addiction-like behaviours in animal models of opioid addiction, and as potential and novel targets to expand therapeutic options to treat OUD. Despite a growing preclinical literature highlighting the role of these potential targets in animal models of opioid addiction, clinical and translational studies for novel treatments of OUD remain limited and inconclusive. Further preclinical and clinical investigations are needed to expand the arsenal of primary treatment options and adjuncts to maximise efficacy and prevent relapse.
Collapse
|
5
|
Smith SL, Dean RL, Todtenkopf MS, Heal DJ. Investigation of the reinforcing potential of samidorphan and naltrexone by fixed and progressive ratio intravenous self-administration testing in heroin-maintained rats. J Psychopharmacol 2019; 33:383-391. [PMID: 30676189 DOI: 10.1177/0269881118822111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Samidorphan is a novel μ-opioid antagonist with low intrinsic activity at κ- and δ-opioid receptors. AIMS Because samidorphan is central nervous system-active, we investigated whether samidorphan (13.6, 40.8, 68 μg/kg/injection) served as a positive reinforcer in rats trained to self-administer heroin on a fixed ratio-5 schedule. Samidorphan's relative reinforcing effect was evaluated by progressive ratio/break-point determination. Naltrexone (13.6, 40.8, 68 μg/kg/injection) and heroin (7.5, 15, 25 μg/kg/injection) were comparators. RESULTS All heroin doses maintained self-administration on fixed ratio-5 and progressive ratio/break-points at levels significantly greater than saline. Samidorphan and naltrexone had similar profiles on fixed ratio-5 with one samidorphan dose serving as a positive reinforcer and one naltrexone dose showing a strong trend ( p=0.053) for positive reinforcement. The numbers of injections of every samidorphan and naltrexone dose were significantly lower than all heroin doses. The numbers of self-administered samidorphan and naltrexone injections/session on fixed ratio-5 were not significantly different from one another. The mean inter-injection intervals for heroin were significantly shorter than for saline, whereas those of samidorphan and naltrexone were not. Progressive ratio break-points for samidorphan and naltrexone were not different from saline except for the highest dose of samidorphan. In addition, the progressive ratio break-points for samidorphan were not significantly different from those of naltrexone and were significantly lower than heroin. The samidorphan unit-doses evaluated in self-administration yielded plasma concentrations ranging between 25-109% and 10-45% of the maximum concentration values in humans. CONCLUSIONS Overall, the profiles of samidorphan and naltrexone, which has no abuse liability, were similar in this model.
Collapse
|
6
|
Wright KN, Hagarty DP, Strong CE, Schoepfer KJ, Kabbaj M. Sex-Dependent Ketamine Addiction-Like Behavior Profile Following Exposure to Chronic Mild Stress. CHRONIC STRESS 2019; 3. [PMID: 31187076 PMCID: PMC6559751 DOI: 10.1177/2470547019832613] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Background Ketamine has rapid antidepressant effects and shows great promise as a novel
treatment for depression, but its limitations including its abuse potential
are poorly understood. Given that the prevalence of depression is twice as
high in women as in men and that depression and substance use disorders are
highly comorbid, we hypothesized that a sex-specific responsivity to
behavioral assays that characterize addiction-like behavior may arise in
rats with prior exposure to chronic stress and therapeutically relevant
ketamine. Methods Male and female rats that underwent chronic mild stress were treated with
four 1.47 mg/kg intravenous ketamine infusions once every fourth day and
underwent operant self-administration of 0.5 mg/kg/infusion ketamine.
Measures of anhedonia (or lack of pleasure, a signature feature of
depression), anxiety-induced neophagia, motivation to obtain ketamine, and
craving were assessed using the sucrose intake test, novelty-suppressed
feeding test, progressive ratio schedule of reinforcement, and incubation of
craving following abstinence, respectively. Finally, dendritic spine density
in the nucleus accumbens core was measured. Results Ketamine infusions reduced anxiety-induced neophagia in both male rats and
female rats but had no effect on measures of anhedonia. Female rats with
prior exposure to chronic mild stress had greater motivation to obtain
ketamine compared to nonstressed female rats, an effect not observed in male
rats. Additionally, female rats who received antidepressant ketamine
infusions had a higher threshold for displaying ketamine addiction-like
behavior than saline-treated female rats as well as increased thin spine
density in the nucleus accumbens core. These effects were not observed in
male rats. Conclusion This study shows that repeated low-dose ketamine does not increase abuse
potential of subsequent ketamine. It also highlights an important
female-specific effect of stress to increase ketamine addiction-like
behavior, which requires further investigation for clinical populations.
Collapse
Affiliation(s)
- Katherine N Wright
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Devin P Hagarty
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Caroline E Strong
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Kristin J Schoepfer
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Mohamed Kabbaj
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| |
Collapse
|
7
|
Strong C, Kabbaj M. On the safety of repeated ketamine infusions for the treatment of depression: Effects of sex and developmental periods. Neurobiol Stress 2018; 9:166-175. [PMID: 30450382 PMCID: PMC6236511 DOI: 10.1016/j.ynstr.2018.09.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/23/2018] [Accepted: 09/04/2018] [Indexed: 12/16/2022] Open
Abstract
In this review, we will discuss the safety of repeated treatments with ketamine for patients with treatment-resistant depression (TRD), a condition in which patients with major depression do not show any clinical improvements following treatments with at least two antidepressant drugs. We will discuss the effects of these treatments in both sexes at different developmental periods. Numerous small clinical studies have shown that a single, low-dose ketamine infusion can rapidly alleviate depressive symptoms and thoughts of suicidality in patients with TRD, and these effects can last for about one week. Interestingly, the antidepressant effects of ketamine can be prolonged with intermittent, repeated infusion regimens and produce more robust therapeutic effects when compared to a single infusion. The safety of such repeated treatments with ketamine has not been thoroughly investigated. Although more studies are needed, some clinical and preclinical reports indicated that repeated infusions of low doses of ketamine may have addictive properties, and suggested that adolescent and adult female subjects may be more sensitive to ketamine's addictive effects. Additionally, during ketamine infusions, many TRD patients report hallucinations and feelings of dissociation and depersonalization, and therefore the effects of repeated treatments of ketamine on cognition must be further examined. Some clinical reports indicated that, compared to women, men are more sensitive to the psychomimetic effects of ketamine. Preclinical studies extended these findings to both adolescent and adult male rodents and showed that male rodents at both developmental periods are more sensitive to ketamine's cognitive-altering effects. Accordingly, in this review we shall focus our discussion on the potential addictive and cognitive-impairing effects of repeated ketamine infusions in both sexes at two important developmental periods: adolescence and adulthood. Although more work about the safety of ketamine is warranted, we hope this review will bring some answers about the safety of treating TRD with repeated ketamine infusions.
Collapse
Affiliation(s)
| | - Mohamed Kabbaj
- Corresponding author. Florida State University, 3300-H, 1115 W. Call St, Tallahassee, FL, 32306, USA.
| |
Collapse
|
8
|
Evaluating the abuse potential of psychedelic drugs as part of the safety pharmacology assessment for medical use in humans. Neuropharmacology 2018; 142:89-115. [PMID: 29427652 DOI: 10.1016/j.neuropharm.2018.01.049] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/07/2018] [Accepted: 01/31/2018] [Indexed: 11/21/2022]
Abstract
Psychedelics comprise drugs come from various pharmacological classes including 5-HT2A agonists, indirect 5-HT agonists, e.g., MDMA, NMDA antagonists and κ-opioid receptor agonists. There is resurgence in developing psychedelics to treat psychiatric disorders with high unmet clinical need. Many, but not all, psychedelics are schedule 1 controlled drugs (CDs), i.e., no approved medical use. For existing psychedelics in development, regulatory approval will require a move from schedule 1 to a CD schedule for drugs with medical use, i.e., schedules 2-5. Although abuse of the psychedelics is well documented, a systematic preclinical and clinical evaluation of the risks they pose in a medical-use setting does not exist. We describe the non-clinical tests required for a regulatory evaluation of abuse/dependence risks, i.e., drug-discrimination, intravenous self-administration and physical dependence liability. A synopsis of the existing data for the various types of psychedelics is provided and we describe our findings with psychedelic drugs in these models. FDA recently issued its guidance on abuse/dependence evaluation of drug-candidates (CDER/FDA, 2017). We critically review the guidance, discuss the impact this document will have on non-clinical abuse/dependence testing, and offer advice on how non-clinical abuse/dependence experiments can be designed to meet not only the expectations of FDA, but also other regulatory agencies. Finally, we offer views on how these non-clinical tests can be refined to provide more meaningful information to aid the assessment of the risks posed by CNS drug-candidates for abuse and physical dependence. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.
Collapse
|
9
|
Chiamulera C, Marzo CM, Balfour DJK. Metabotropic glutamate receptor 5 as a potential target for smoking cessation. Psychopharmacology (Berl) 2017; 234:1357-1370. [PMID: 27847973 DOI: 10.1007/s00213-016-4487-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/07/2016] [Indexed: 12/21/2022]
Abstract
RATIONALE Most habitual smokers find it difficult to quit smoking because they are dependent upon the nicotine present in tobacco smoke. Tobacco dependence is commonly treated pharmacologically using nicotine replacement therapy or drugs, such as varenicline, that target the nicotinic receptor. Relapse rates, however, remain high, and there remains a need to develop novel non-nicotinic pharmacotherapies for the dependence that are more effective than existing treatments. OBJECTIVE The purpose of this paper is to review the evidence from preclinical and clinical studies that drugs that antagonise the metabotropic glutamate receptor 5 (mGluR5) in the brain are likely to be efficacious as treatments for tobacco dependence. RESULTS Imaging studies reveal that chronic exposure to tobacco smoke reduces the density of mGluR5s in human brain. Preclinical results demonstrate that negative allosteric modulators (NAMs) at mGluR5 attenuate both nicotine self-administration and the reinstatement of responding evoked by exposure to conditioned cues paired with nicotine delivery. They also attenuate the effects of nicotine on brain dopamine pathways implicated in addiction. CONCLUSIONS Although mGluR5 NAMs attenuate most of the key facets of nicotine dependence, they potentiate the symptoms of nicotine withdrawal. This may limit their value as smoking cessation aids. The NAMs that have been employed most widely in preclinical studies of nicotine dependence have too many "off-target" effects to be used clinically. However, newer mGluR5 NAMs have been developed for clinical use in other indications. Future studies will determine if these agents can also be used effectively and safely to treat tobacco dependence.
Collapse
Affiliation(s)
- Cristiano Chiamulera
- Neuropsychopharmacology Lab., Section Pharmacology, Department Diagnostic and Public Health, University of Verona, P.le Scuro 10, 37134, Verona, Italy.
| | - Claudio Marcello Marzo
- Neuropsychopharmacology Lab., Section Pharmacology, Department Diagnostic and Public Health, University of Verona, P.le Scuro 10, 37134, Verona, Italy
| | - David J K Balfour
- Division of Neuroscience, University of Dundee Medical School, Mailbox 6, Ninewells Hospital, Dundee, DD1 9SY, UK
| |
Collapse
|
10
|
Wright KN, Strong CE, Addonizio MN, Brownstein NC, Kabbaj M. Reinforcing properties of an intermittent, low dose of ketamine in rats: effects of sex and cycle. Psychopharmacology (Berl) 2017; 234:393-401. [PMID: 27837330 PMCID: PMC5384643 DOI: 10.1007/s00213-016-4470-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 10/27/2016] [Indexed: 11/30/2022]
Abstract
RATIONALE Repeated intermittent exposure to ketamine has rapid and long-lasting antidepressant effects, but the abuse potential has only been assessed at high doses. Furthermore, while females are more susceptible to depression and more sensitive to ketamine's antidepressant-like effects, the abuse potential for ketamine in females is unknown. OBJECTIVES The objectives of this study are to determine the reinforcing properties of low-dose intermittent ketamine in adult rats of both sexes and determine whether cycling gonadal hormones influence females' response to ketamine. In male rats, we also aimed to determine whether reinstatement to intermittent ketamine is comparable to intermittent cocaine. METHODS Male rats intravenously self-administered cocaine (0.75 mg/kg/infusion) or ketamine (0.1 mg/kg/infusion) once every fourth day, while intact cycling female rats self-administered ketamine only during preidentified stages of their 4-day estrus cycle, when gonadal hormones are either high (proestrus) or low (diestrus). After acquiring self-administration, rats underwent daily extinction training followed by cue-primed and drug-primed reinstatement to assess drug-seeking behavior. RESULTS Diestrus-trained females fail to maintain ketamine self-administration and did not display reinstatement to ketamine-paired cues. Males and proestrus-trained females reinstated to ketamine-paired cues. Ketamine-primed reinstatement was dependent on simultaneous cue presentation. Male rats reinstated to cocaine priming independent of cue presentation. CONCLUSION These findings indicate that females's responsivity to this dose of ketamine depends on stage of cycle, as only proestrus-trained females and males respond to ketamine's reinforcing effects under this treatment paradigm.
Collapse
Affiliation(s)
- Katherine N. Wright
- Program in Neuroscience, Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Caroline E. Strong
- Program in Neuroscience, Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Marjorie N. Addonizio
- Program in Neuroscience, Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA
| | - Naomi C. Brownstein
- Department of Behavioral Sciences and Social Medicine, Florida State University, Tallahassee, FL, USA,Department of Statistics, Florida State University, Tallahassee, FL, USA
| | - Mohamed Kabbaj
- Program in Neuroscience, Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA. .,College of Medicine, Department of Biomedical Sciences, Florida State University, 1115 W. Call St., Tallahassee, FL, 32306, USA.
| |
Collapse
|
11
|
Ketamine abuse potential and use disorder. Brain Res Bull 2016; 126:68-73. [DOI: 10.1016/j.brainresbull.2016.05.016] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 05/26/2016] [Accepted: 05/30/2016] [Indexed: 02/07/2023]
|
12
|
The ketamine-like compound methoxetamine substitutes for ketamine in the self-administration paradigm and enhances mesolimbic dopaminergic transmission. Psychopharmacology (Berl) 2016; 233:2241-51. [PMID: 27020786 DOI: 10.1007/s00213-016-4275-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 03/09/2016] [Indexed: 01/26/2023]
Abstract
RATIONALE Recently, an increasing number of emergency cases due to a novel ketamine-like drug, methoxetamine (MXE), were reported in several countries. However, very little is known about the neuropsychopharmacological and reinforcing profile of this compound. OBJECTIVES Our study aims to investigate the effects of MXE on self-administration (SA) behaviour in comparison to ketamine and on dopaminergic transmission. METHODS A SA substitution study was performed in male rats trained to intravenously (IV) self-administer ketamine. At responding stability, rats were exposed to sequential phases of MXE substitution at different dosages (starting from 0.5 and then decreasing to 0.25 and 0.125 mg/kg). Standard electrophysiological techniques were used to record changes in firing activities of ventral tegmental area (VTA) dopamine neurons projecting to the nucleus accumbens (NAc) shell after acute injection of cumulative doses of MXE (0.031-0.5 mg/kg IV). Finally, in vivo microdialysis was performed in freely moving rats to evaluate the effect of acute MXE administration (0.125, 0.25 and 0.5 mg/kg IV) on dopamine release in the NAc shell. RESULTS MXE 0.125 and 0.25 mg/kg, but not 0.5 mg/kg, substituted for ketamine SA. MXE also induced a dose-dependent stimulation of firing rate (p < 0.0001) and burst firing (p < 0.05) of NAc-projecting VTA dopamine neurons. Consistently, MXE significantly (p < 0.05) increased dopamine extracellular levels in the NAc shell at 0.5 and 0.25 mg/kg with different time onsets, i.e. at 40 and 100 min, respectively. CONCLUSIONS This study, while confirming the reinforcing effects of MXE, highlights an electrophysiological and neurochemical profile predictive of its addictive properties.
Collapse
|
13
|
Akkus F, Treyer V, Johayem A, Ametamey SM, Mancilla BG, Sovago J, Buck A, Hasler G. Association of Long-Term Nicotine Abstinence With Normal Metabotropic Glutamate Receptor-5 Binding. Biol Psychiatry 2016; 79:474-80. [PMID: 25861697 DOI: 10.1016/j.biopsych.2015.02.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 01/23/2015] [Accepted: 02/16/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Nicotine addiction is a major public health problem and is associated with primary glutamatergic dysfunction. We recently showed marked global reductions in metabotropic glutamate receptor type 5 (mGluR5) binding in smokers and recent ex-smokers (average abstinence duration of 25 weeks). The goal of this study was to examine the role of mGluR5 downregulation in nicotine addiction by investigating a group of long-term ex-smokers (abstinence >1.5 years), and to explore associations between mGluR5 binding and relapse in recent ex-smokers. METHODS Images of mGluR5 receptor binding were acquired in 14 long-term ex-smokers, using positron emission tomography with radiolabeled [11C]ABP688, which binds to an allosteric site with high specificity. RESULTS Long-term ex-smokers and individuals who had never smoked showed no differences in mGluR5 binding in any of the brain regions examined. Long-term ex-smokers showed significantly higher mGluR5 binding than recent ex-smokers, most prominently in the frontal cortex (42%) and thalamus (57%). CONCLUSIONS Our findings suggest that downregulation of mGluR5 is a pathogenetic mechanism underlying nicotine dependence and the high relapse rate in individuals previously exposed to nicotine. Therefore, mGluR5 receptor binding appears to be an effective biomarker in smoking and a promising target for the discovery of novel medication for nicotine dependence and other substance-related disorders.
Collapse
Affiliation(s)
- Funda Akkus
- Division of Molecular Psychiatry (FA, GH), Translational Research Center, University Hospital of Psychiatry, University of Bern, Bern, Switzerland
| | - Valerie Treyer
- PET Center (VT, AB), Division of Nuclear Medicine, University Hospital, and Center for Radiopharmaceutical Science of ETH, PSI
| | - Anass Johayem
- Department of Chemistry and Applied Biosciences of ETH (AJ, SMA), USZ, Zurich, Switzerland
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences of ETH (AJ, SMA), USZ, Zurich, Switzerland
| | - Baltazar Gomez Mancilla
- Novartis Institute for BioMedical Research (BGM, JS), Novartis Pharma AG, Basel, Switzerland
| | - Judit Sovago
- Novartis Institute for BioMedical Research (BGM, JS), Novartis Pharma AG, Basel, Switzerland
| | - Alfred Buck
- PET Center (VT, AB), Division of Nuclear Medicine, University Hospital, and Center for Radiopharmaceutical Science of ETH, PSI
| | - Gregor Hasler
- Division of Molecular Psychiatry (FA, GH), Translational Research Center, University Hospital of Psychiatry, University of Bern, Bern, Switzerland.
| |
Collapse
|
14
|
Mihov Y, Hasler G. Negative Allosteric Modulators of Metabotropic Glutamate Receptors Subtype 5 in Addiction: a Therapeutic Window. Int J Neuropsychopharmacol 2016; 19:pyw002. [PMID: 26802568 PMCID: PMC4966271 DOI: 10.1093/ijnp/pyw002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/08/2016] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Abundant evidence at the anatomical, electrophysiological, and molecular levels implicates metabotropic glutamate receptor subtype 5 (mGluR5) in addiction. Consistently, the effects of a wide range of doses of different mGluR5 negative allosteric modulators (NAMs) have been tested in various animal models of addiction. Here, these studies were subjected to a systematic review to find out if mGluR5 NAMs have a therapeutic potential that can be translated to the clinic. METHODS Literature on consumption/self-administration and reinstatement of drug seeking as outcomes of interest published up to April 2015 was retrieved via PubMed. The review focused on the effects of systemic (i.p., i.v., s.c.) administration of the mGluR5 NAMs 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) and 2-Methyl-6-(phenylethynyl)pyridine (MPEP) on paradigms with cocaine, ethanol, nicotine, and food in rats. RESULTS MTEP and MPEP were found to reduce self-administration of cocaine, ethanol, and nicotine at doses ≥1mg/kg and 2.5mg/kg, respectively. Dose-response relationship resembled a sigmoidal curve, with low doses not reaching statistical significance and high doses reliably inhibiting self-administration of drugs of abuse. Importantly, self-administration of cocaine, ethanol, and nicotine, but not food, was reduced by MTEP and MPEP in the dose range of 1 to 2mg/kg and 2.5 to 3.2mg/kg, respectively. This dose range corresponds to approximately 50% to 80% mGluR5 occupancy. Interestingly, the limited data found in mice and monkeys showed a similar therapeutic window. CONCLUSION Altogether, this review suggests a therapeutic window for mGluR5 NAMs that can be translated to the treatment of substance-related and addictive disorders.
Collapse
Affiliation(s)
- Yoan Mihov
- Division of Molecular Psychiatry, Translational Research Center, Psychiatric University Hospital, University of Bern, Switzerland
| | - Gregor Hasler
- Division of Molecular Psychiatry, Translational Research Center, Psychiatric University Hospital, University of Bern, Switzerland
| |
Collapse
|
15
|
Metabotropic glutamate receptor 5 – a promising target in drug development and neuroimaging. Eur J Nucl Med Mol Imaging 2016; 43:1151-70. [DOI: 10.1007/s00259-015-3301-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
|
16
|
D'Souza MS. Glutamatergic transmission in drug reward: implications for drug addiction. Front Neurosci 2015; 9:404. [PMID: 26594139 PMCID: PMC4633516 DOI: 10.3389/fnins.2015.00404] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/12/2015] [Indexed: 12/12/2022] Open
Abstract
Individuals addicted to drugs of abuse such as alcohol, nicotine, cocaine, and heroin are a significant burden on healthcare systems all over the world. The positive reinforcing (rewarding) effects of the above mentioned drugs play a major role in the initiation and maintenance of the drug-taking habit. Thus, understanding the neurochemical mechanisms underlying the reinforcing effects of drugs of abuse is critical to reducing the burden of drug addiction in society. Over the last two decades, there has been an increasing focus on the role of the excitatory neurotransmitter glutamate in drug addiction. In this review, pharmacological and genetic evidence supporting the role of glutamate in mediating the rewarding effects of the above described drugs of abuse will be discussed. Further, the review will discuss the role of glutamate transmission in two complex heterogeneous brain regions, namely the nucleus accumbens (NAcc) and the ventral tegmental area (VTA), which mediate the rewarding effects of drugs of abuse. In addition, several medications approved by the Food and Drug Administration that act by blocking glutamate transmission will be discussed in the context of drug reward. Finally, this review will discuss future studies needed to address currently unanswered gaps in knowledge, which will further elucidate the role of glutamate in the rewarding effects of drugs of abuse.
Collapse
Affiliation(s)
- Manoranjan S D'Souza
- Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University Ada, OH, USA
| |
Collapse
|
17
|
Qi C, Wang X, Ge F, Li Y, Shen F, Wang J, Cui C. mGluR5 in the nucleus accumbens shell regulates morphine-associated contextual memory through reactive oxygen species signaling. Addict Biol 2015; 20:927-40. [PMID: 25736529 DOI: 10.1111/adb.12222] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Emerging evidence indicates that metabotropic glutamate receptor 5 (mGluR5) critically modulates drug and drug-related behaviors. However, the role of mGluR5 in the opiate-induced contextual memory remains unclear. Here, we found that microinfusion of the mGluR5 antagonist 3-((2-Methyl-1,3-thiazol-4-yl)ethynyl)pyridine (MTEP) into the nucleus accumbens (NAc) shell, but not into the core, significantly attenuated the expression of morphine conditioned place preference (CPP) in rats. Following the expression of morphine CPP, the protein level of membrane mGluR5 was selectively increased in the NAc shell. In primary striatal neurons, we observed that treatment with the mGluR5 agonist CHPG increased the phosphorylation level of extracellular signal-regulated kinase (ERK), which was dependent on the mGluR5-inositol-1,4,5-trisphosphate-reactive oxygen species (ROS) pathway. Moreover, the microinjection of the ROS scavenger Tempol into the NAc shell of rats blocked the expression of morphine CPP. Further, the administration of t-BOOH, a ROS donor, into the NAc shell rescued the retrieval impairment of morphine CPP produced by MTEP. Our previous study demonstrated that the expression of morphine CPP increased the phosphorylation of ERK selectively in the NAc shell. Thus, results of the present study suggest that mGluR5 in the NAc shell, but not in the core, is essential for the retrieval of morphine contextual memory, which is mediated at least in part, through the ROS/ERK signaling pathway. Uncovering the molecular basis of opiate contextual memory will benefit the development of new therapeutic approaches for the treatment of opiate addiction.
Collapse
Affiliation(s)
- Chong Qi
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Xinjuan Wang
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Feifei Ge
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Yijing Li
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Fang Shen
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Junkai Wang
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| | - Cailian Cui
- Department of Neurobiology; School of Basic Medical Sciences; Key Laboratory for Neuroscience of the Ministry of Education and National Health and Family Planning Commission; Neuroscience Research Institute; Peking University; Beijing China
| |
Collapse
|
18
|
Blockade of mGluR5 in the nucleus accumbens shell but not core attenuates heroin seeking behavior in rats. Acta Pharmacol Sin 2014; 35:1485-92. [PMID: 25399651 DOI: 10.1038/aps.2014.93] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 08/20/2014] [Indexed: 11/08/2022] Open
Abstract
AIM Glutamatergic neurotransmission in the nucleus accumbens (NAc) is crucial for the relapse to heroin seeking. The aim of this study was to determine whether mGluR5 in the NAc core or shell involved in heroin seeking behavior in rats. METHODS Male SD rats were self-administered heroin under a fixed-ratio 1 (FR1) reinforcement schedule for 14 d, and subsequently withdrawn for 2 weeks. The selective mGluR5 antagonist 2-methyl-6-phenylethynyl-pyridine (MPEP, 5, 15 and 50 nmol per side) was then microinjected into the NAc core or shell 10 min before a heroin-seeking test induced by context, cues or heroin priming. RESULTS Microinjection of MPEP into the NAc shell dose-dependently decreased the heroin seeking induced by context, cues or heroin priming. In contrast, microinjection of MPEP into the NAc core did not alter the heroin seeking induced by cues or heroin priming. In addition, microinjection with MPEP (15 nmol per side) in the NAc shell reversed both the percentage of open arms entries (OE%) and the percentage of time spent in open arms (OT%) after heroin withdrawal. Microinjection of MPEP (50 nmol per side) in the striatum as a control location did not affect the heroin seeking behavior. Microinjection of MPEP in the 3 locations did not change the locomotion activities. CONCLUSION Blockade of mGluR5 in NAc shell in rats specifically suppresses the relapse to heroin-seeking and anxiety-like behavior, suggesting that mGluR5 antagonists may be a potential candidate for the therapy of heroin addiction.
Collapse
|
19
|
Pomierny-Chamioło L, Rup K, Pomierny B, Niedzielska E, Kalivas PW, Filip M. Metabotropic glutamatergic receptors and their ligands in drug addiction. Pharmacol Ther 2014; 142:281-305. [DOI: 10.1016/j.pharmthera.2013.12.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/02/2013] [Indexed: 02/07/2023]
|
20
|
Hulka LM, Treyer V, Scheidegger M, Preller KH, Vonmoos M, Baumgartner MR, Johayem A, Ametamey SM, Buck A, Seifritz E, Quednow BB. Smoking but not cocaine use is associated with lower cerebral metabotropic glutamate receptor 5 density in humans. Mol Psychiatry 2014; 19:625-32. [PMID: 23628984 DOI: 10.1038/mp.2013.51] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 03/18/2013] [Indexed: 12/18/2022]
Abstract
Long-lasting neuroadaptations in the glutamatergic corticostriatal circuitry have been suggested to be responsible for the persisting nature of drug addiction. In particular, animal models have linked the metabotropic glutamate receptor 5 (mGluR5) to drug-seeking behavior and extinction learning. Accordingly, blocking mGluR5s attenuated self-administration of cocaine and other addictive drugs in rats. How these animal findings extend to humans remains unclear. Therefore, we investigated if human cocaine users (CU) exhibit altered mGluR5 availability compared with drug-naïve control subjects. Seventeen male controls (11 smokers) and 18 male cocaine users (13 smokers) underwent positron emission tomography with (11)C-ABP688 to quantify mGluR5 availability in 12 volumes of interest in addiction-related brain areas. Drug use was assessed by self-report and quantitative hair toxicology. CU and controls did not significantly differ in regional mGluR5 availability. In contrast, smokers (n=24) showed significantly lower mGluR5 density throughout the brain (mean 20%) compared with non-smokers (n=11). In terms of effect sizes, lower mGluR5 availability was most pronounced in the caudate nucleus (d=1.50, 21%), insula (d=1.47, 20%), and putamen (d=1.46, 18%). Duration of smoking abstinence was positively associated with mGluR5 density in all brain regions of interest, indicating that lower mGluR5 availability was particularly pronounced in individuals who had smoked very recently. Specifically tobacco smoking was associated with lower mGluR5 availability in both CU and controls, while cocaine use was not linked to detectable mGluR5 alterations. These findings have important implications regarding the development of novel pharmacotherapies aimed at facilitating smoking cessation.
Collapse
Affiliation(s)
- L M Hulka
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - V Treyer
- Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - M Scheidegger
- 1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
| | - K H Preller
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - M Vonmoos
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - M R Baumgartner
- Institute of Legal Medicine, University of Zurich, Zurich, Switzerland
| | - A Johayem
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland
| | - S M Ametamey
- 1] Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - A Buck
- 1] Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - E Seifritz
- 1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - B B Quednow
- 1] Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| |
Collapse
|
21
|
Managò F, Lopez S, Oliverio A, Amalric M, Mele A, De Leonibus E. Interaction between the mGlu receptors 5 antagonist, MPEP, and amphetamine on memory and motor functions in mice. Psychopharmacology (Berl) 2013. [PMID: 23192313 DOI: 10.1007/s00213-012-2925-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
RATIONALE Metabotropic glutamate mGlu receptors 5 (mGluR5) receptors are abundant in corticolimbic circuitry where they modulate glutamate and dopamine signal transduction. OBJECTIVES In this study, we explored the hypothesis that mGluR5 antagonist, (2-methyl-6-(phenylethynyl)pyridine hydrochloride) (MPEP), facilitates dopamine-dependent effects on memory and motor functions. METHODS To this aim, we examined the effects of different doses (from 0 to 24 mg/kg) of the mGluR5 antagonist, MPEP, on the modulation of amphetamine-dependent behaviors, namely passive avoidance, locomotor activity, and rotation behavior in intact and dopamine-depleted CD1 male mice. RESULTS We demonstrated that a low dose (3 mg/kg) of MPEP, which is void of behavioral effects on its own, facilitates amphetamine-induced effects independently on the behavior measured both in naïve and in dopamine-lesioned mice; this synergistic effect is lost when higher doses of MPEP are used. CONCLUSION The results are discussed in terms of possible balance between dopamine and glutamate activity in regulating the proper fine tuning of information processing.
Collapse
Affiliation(s)
- Francesca Managò
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Università degli Studi di Roma "La Sapienza", Rome, Italy
| | | | | | | | | | | |
Collapse
|
22
|
Marked global reduction in mGluR5 receptor binding in smokers and ex-smokers determined by [11C]ABP688 positron emission tomography. Proc Natl Acad Sci U S A 2012; 110:737-42. [PMID: 23248277 DOI: 10.1073/pnas.1210984110] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Nicotine addiction is a major public health problem, resulting in primary glutamatergic dysfunction. We measured the glutamate receptor binding in the human brain and provided direct evidence for the abnormal glutamate system in smokers. Because antagonism of the metabotropic glutamate receptor 5 (mGluR5) reduced nicotine self-administration in rats and mice, mGluR5 is suggested to be involved in nicotine addiction. mGluR5 receptor binding specifically to an allosteric site was observed by using positron emission tomography with [(11)C]ABP688. We found a marked global reduction (20.6%; P < 0.0001) in the mGluR5 distribution volume ratio (DVR) in the gray matter of 14 smokers. The most prominent reductions were found in the bilateral medial orbitofrontal cortex. Compared with 14 nonsmokers, 14 ex-smokers had global reductions in the average gray matter mGluR5 DVR (11.5%; P < 0.005), and there was a significant difference in average gray matter mGluR5 DVR between smokers and ex-smokers (9.2%; P < 0.01). Clinical variables reflecting current nicotine consumption, dependence and abstinence were not correlated with mGluR5 DVR. This decrease in mGluR5 receptor binding may be an adaptation to chronic increases in glutamate induced by chronic nicotine administration, and the decreased down-regulation seen in the ex-smokers could be due to incomplete recovery of the receptors, especially because the ex-smokers were abstinent for only 25 wk on average. These results encourage the development and testing of drugs against addiction that directly target the glutamatergic system.
Collapse
|
23
|
Abstract
As the major excitatory neurotransmitter in the brain, glutamate plays an undisputable integral role in opiate addiction. This relates, in part, to the fact that addiction is a disorder of learning and memory, and glutamate is required for most types of memory formation. As opiate addiction develops, the addict becomes conditioned to engage in addictive behaviors, and these behaviors can be triggered by opiate-associated cues during abstinence, resulting in relapse. Some medications for opiate addiction exert their therapeutic effects at glutamate receptors, especially the NMDA receptor. Understanding the neural circuits controlling opiate addiction, and the locus of glutamate's actions within these circuits, will help guide the development of targeted pharmacotherapeutics for relapse.
Collapse
Affiliation(s)
- Jamie Peters
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, 1081BT Amsterdam, The Netherlands
| | | |
Collapse
|
24
|
Rewarding and reinforcing effects of the NMDA receptor antagonist–benzodiazepine combination, zoletil®: Difference between acute and repeated exposure. Behav Brain Res 2012; 233:434-42. [DOI: 10.1016/j.bbr.2012.05.038] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 05/21/2012] [Accepted: 05/22/2012] [Indexed: 01/01/2023]
|
25
|
Brown RM, Stagnitti MR, Duncan JR, Lawrence AJ. The mGlu5 receptor antagonist MTEP attenuates opiate self-administration and cue-induced opiate-seeking behaviour in mice. Drug Alcohol Depend 2012; 123:264-8. [PMID: 22129842 DOI: 10.1016/j.drugalcdep.2011.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/02/2011] [Accepted: 11/03/2011] [Indexed: 10/14/2022]
Abstract
The mGlu5 receptor (mGluR5) has been implicated in the rewarding effect of various drugs of abuse and drug-seeking behaviour. In the present study we investigated the impact of antagonism of mGluR5 with the selective negative allosteric, modulator 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) on operant self-administration of morphine as well as cue-induced drug-seeking in adult CD1 mice. Administration of MTEP (20 mg/kg, i.p.) attenuated operant responding for morphine (0.1 mg/kg/infusion) and cue-induced morphine-seeking after a period of forced abstinence. Collectively, these data implicate mGluR5 in the reinforcing effects of opiates and support the proposition that mGluR5 is a potential therapeutic target for treatment of drug addiction.
Collapse
Affiliation(s)
- Robyn M Brown
- Florey Neuroscience Institutes, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | | | | |
Collapse
|
26
|
Martin-Fardon R, Weiss F. (-)-2-oxa-4-aminobicylco[3.1.0]hexane-4,6-dicarboxylic acid (LY379268) and 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]piperidine (MTEP) similarly attenuate stress-induced reinstatement of cocaine seeking. Addict Biol 2012; 17:557-64. [PMID: 21790902 DOI: 10.1111/j.1369-1600.2011.00345.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) have been implicated in the regulation of anxiety, stress responses and the neurobehavioral effects of psychostimulants. The present study was designed to examine whether antagonizing mGluR5 or activating mGluR2/3 prevents stress-induced reinstatement of cocaine seeking. Male Wistar rats were trained to self-administer cocaine and then subjected to daily extinction training for 2 weeks. Subsequent exposure to 15 minutes of intermittent footshock elicited robust reinstatement of responding at the previously active lever. Both the selective mGluR5 antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]piperidine (MTEP) (0-3 mg/kg, intraperitoneally) and the selective mGluR2/3 agonist (-)-2-oxa-4-aminobicylco[3.1.0]hexane-4,6-dicarboxylic acid (LY379268) (0-3 mg/kg, subcutaneously) prevented cocaine seeking induced by footshock stress following the same dose-response function. The data show that although mGluR2/3 and mGluR5 are differentially located on synaptic compartments, both LY379268 and MTEP produced the same behavioral effects in reducing stress-induced reinstatement. These results are important because they demonstrate that a reduction in glutamate-mediated neural excitability (albeit via different mechanisms of action) reverses footshock-induced reinstatement and suggest that pharmacological manipulations of mGluR2/3 and mGluR5 can prevent the effects of stress, a major precipitating factor for relapse. These findings further confirm that mGluR2/3 or mGluR5 are promising targets for relapse prevention.
Collapse
Affiliation(s)
- Rémi Martin-Fardon
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | | |
Collapse
|
27
|
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]
|
28
|
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
|
29
|
Duncan JR, Lawrence AJ. The role of metabotropic glutamate receptors in addiction: evidence from preclinical models. Pharmacol Biochem Behav 2011; 100:811-24. [PMID: 21443897 DOI: 10.1016/j.pbb.2011.03.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/21/2011] [Accepted: 03/16/2011] [Indexed: 11/25/2022]
Abstract
Addiction is a chronic disorder characterised by repeated bouts of drug taking, abstinence and relapse. The addicted state may be in part due to drug-induced neuroadaptations in the mesocorticolimbic and corticostriatal pathways. Recently focus has been on the role of aberrant glutamate transmission and its contribution to the hierarchical control over these systems. This review will expand our current knowledge of the most recent advances that have been made in preclinical animal models that provide evidence that implicate metabotropic glutamate receptors (mGluRs) in contributing to the neuroadaptations pertinent to addiction, as well as the role of Homer proteins in regulating these responses. The recent discovery of receptor mosaics will be discussed which add an additional dimension to the complexity of understanding the mechanism of glutamate mediated behaviours. Finally this review introduces a new area related to glutamatergic responses, namely microRNAs, that may become pivotal in directing our future understanding of how to best target intervention strategies to prevent addictive behaviours.
Collapse
Affiliation(s)
- Jhodie R Duncan
- Florey Neuroscience Institutes, University of Melbourne, Parkville, Vic., 3010, Australia.
| | | |
Collapse
|
30
|
Manzanedo C, Aguilar MA, Miñarro J, Rodríguez-Arias M. Effects of CNQX and MPEP on sensitization to the rewarding effects of morphine. Eur J Pharmacol 2011; 654:42-6. [DOI: 10.1016/j.ejphar.2010.11.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/15/2010] [Accepted: 11/26/2010] [Indexed: 01/02/2023]
|
31
|
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
|
32
|
Veeneman MMJ, Boleij H, Broekhoven MH, Snoeren EMS, Guitart Masip M, Cousijn J, Spooren W, Vanderschuren LJMJ. Dissociable roles of mGlu5 and dopamine receptors in the rewarding and sensitizing properties of morphine and cocaine. Psychopharmacology (Berl) 2011; 214:863-76. [PMID: 21120457 PMCID: PMC3063544 DOI: 10.1007/s00213-010-2095-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 11/03/2010] [Indexed: 02/07/2023]
Abstract
RATIONALE Drugs of abuse are initially used because of their rewarding properties. As a result of repeated drug exposure, sensitization to certain behavioral effects of drugs occurs, which may facilitate the development of addiction. Recent studies have implicated the metabotropic glutamate receptor 5 (mGlu5 receptor) in drug reward, but its role in sensitization is unclear. Stimulation of dopamine receptors plays an important role in drug reward, but not in the sensitizing properties of cocaine and morphine. OBJECTIVE This study aims to evaluate the role of mGlu5 and dopamine receptors in the development of cocaine- and morphine-induced conditioned place preference (CPP) and psychomotor sensitization. MATERIALS AND METHODS Rats were treated with the mGlu5 receptor antagonist MTEP (0, 1, 3, and 10 mg/kg, i.p.) or the dopamine receptor antagonist α-flupenthixol (0, 0.125, 0.25, and 0.5 mg/kg, i.p.) during place conditioning with either morphine (3 mg/kg, s.c.) or cocaine (15 mg/kg, i.p.). Furthermore, MTEP (1 mg/kg, i.p.) or α-flupenthixol (0.5 mg/kg, i.p.) was co-administered during cocaine (30 mg/kg, i.p.) or morphine (3.0 mg/kg, s.c.) pretreatment and psychomotor sensitization was tested 3 weeks post-treatment. RESULTS MTEP attenuated the development of morphine- but not cocaine-induced CPP. In contrast, MTEP suppressed the development of cocaine- but not morphine-induced psychomotor sensitization. α-Flupenthixol blocked the development of both cocaine- and morphine-induced CPP but did not affect the development of sensitization to either drug. CONCLUSION Dopamine receptor stimulation mediates cocaine and morphine reward but not sensitization. In contrast, the role of mGlu5 receptors in reward and sensitization is drug-specific.
Collapse
Affiliation(s)
- M. M. J. Veeneman
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - H. Boleij
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - M. H. Broekhoven
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - E. M. S. Snoeren
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - M. Guitart Masip
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - J. Cousijn
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - W. Spooren
- F. Hoffmann-La Roche, CNS-DTA, Translational Medicine, Basel, Switzerland
| | - L. J. M. J. Vanderschuren
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands ,Department of Animals in Science and Society, Division of Behavioural Neuroscience, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| |
Collapse
|
33
|
Operant sensation seeking requires metabotropic glutamate receptor 5 (mGluR5). PLoS One 2010; 5:e15085. [PMID: 21152045 PMCID: PMC2994905 DOI: 10.1371/journal.pone.0015085] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 10/18/2010] [Indexed: 11/19/2022] Open
Abstract
Pharmacological and genetic studies have suggested that the metabotropic glutamate receptor 5 (mGluR5) is critically involved in mediating the reinforcing effects of drugs of abuse, but not food. The purpose of this study was to use mGluR5 knockout (KO), heterozygous (Het), and wildtype (WT) mice to determine if mGluR5 modulates operant sensation seeking (OSS), an operant task that uses varied sensory stimuli as a reinforcer. We found that mGluR5 KO mice had significantly reduced OSS responding relative to WT mice, while Het mice displayed a paradoxical increase in OSS responding. Neither KO nor Het mice exhibited altered operant responding for food as a reinforcer. Further, we assessed mGluR5 KO, Het and WT mice across a battery of cocaine locomotor, place preference and anxiety related tests. Although KO mice showed expected differences in some locomotor and anxiety measures, Het mice either exhibited no phenotype or an intermediate one. In total, these data demonstrate a key role for mGluR5 in OSS, indicating an important role for this receptor in reinforcement-based behavior.
Collapse
|
34
|
Besheer J, Grondin JJ, Cannady R, Sharko AC, Faccidomo S, Hodge CW. Metabotropic glutamate receptor 5 activity in the nucleus accumbens is required for the maintenance of ethanol self-administration in a rat genetic model of high alcohol intake. Biol Psychiatry 2010; 67:812-22. [PMID: 19897175 PMCID: PMC2854174 DOI: 10.1016/j.biopsych.2009.09.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 09/04/2009] [Accepted: 09/16/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Systemic modulation of Group I and II metabotropic glutamate receptors (mGluRs) regulate ethanol self-administration in a variety of animal models. Although these receptors are expressed in reward-related brain regions, the anatomical specificity of their functional involvement in ethanol self-administration remains to be characterized. This study sought to evaluate the functional role of Group I (mGluR5) and Group II (mGluR2/3) in mesocorticolimbic brain regions in ethanol self-administration. METHODS Alcohol-preferring (P) rats, a genetic model of high alcohol drinking, were trained to self-administer ethanol (15% v/v) versus water in operant conditioning chambers. Effects of brain site-specific infusion of the mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) and the mGluR2/3 agonist were then assessed on the maintenance of self-administration. RESULTS Microinjection of the mGluR5 antagonist MPEP in the nucleus accumbens reduced ethanol self-administration at a dose that did not alter locomotor activity. By contrast, infusion of the mGluR2/3 agonist LY379268 in the nucleus accumbens reduced self-administration and produced nonspecific reductions in locomotor activity. The mGluR5 involvement showed anatomical specificity as evidenced by lack of effect of MPEP infusion in the dorsomedial caudate or medial prefrontal cortex on ethanol self-administration. To determine reinforcer specificity, P-rats were trained to self-administer sucrose (.4% w/v) versus water, and effects of intra-accumbens MPEP were tested. The MPEP did not alter sucrose self-administration or motor behavior. CONCLUSIONS These results suggest that mGluR5 activity specifically in the nucleus accumbens is required for the maintenance of ethanol self-administration in individuals with genetic risk for high alcohol consumption.
Collapse
|
35
|
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
|
36
|
Olive MF. Metabotropic glutamate receptor ligands as potential therapeutics for addiction. ACTA ACUST UNITED AC 2009; 2:83-98. [PMID: 19630739 DOI: 10.2174/1874473710902010083] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
There is now compelling evidence that the excitatory amino acid neurotransmitter glutamate plays a pivotal role in drug addiction and alcoholism. As a result, there has been increasing interest in developing glutamate-based therapies for the treatment of addictive disorders. Receptors for glutamate are primarily divided into two classes: ionotropic glutamate receptors (iGluRs) that mediate fast excitatory glutamate transmission, and metabotropic glutamate receptors (mGluRs), which are G-protein coupled receptors that mediate slower, modulatory glutamate transmission. Most iGluR antagonists, while showing some efficacy in animal models of addiction, exhibit serious side effects when tested in humans. mGluR ligands, on the other hand, which have been advanced to testing in clinical trials for various medical conditions, have demonstrated the ability to reduce drug reward, reinforcement, and relapse-like behaviors in animal studies. mGluR ligands that have been shown to be primarily effective are Group I (mGluR1 and mGluR5) negative allosteric modulators and Group II (mGluR2 and mGluR3) orthosteric presynaptic autoreceptor agonists. In this review, we will summarize findings from animal studies suggesting that these mGluR ligands may be of potential benefit in reducing on-going drug self-administration and may aid in the prevention of relapse. The neuroanatomical distribution of mGluR1, mGluR2/3, and mGluR5 receptors and the pharmacological properties of Group I negative allosteric modulators and Group II agonists will also be overviewed. Finally, we will discuss the current status of mGluR ligands in human clinical trials.
Collapse
Affiliation(s)
- M Foster Olive
- Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, MSC 861, Charleston, SC 29425, USA.
| |
Collapse
|
37
|
van der Kam EL, De Vry J, Tzschentke TM. The mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) supports intravenous self-administration and induces conditioned place preference in the rat. Eur J Pharmacol 2009; 607:114-20. [PMID: 19326478 DOI: 10.1016/j.ejphar.2009.01.049] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We recently reported that the mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) reduces intravenous self-administration of ketamine and, to a lesser extent, heroin in rats. We also found that MPEP potentiates conditioned place preference induced by these drugs, suggesting that the reduction of self-administration results from an MPEP-induced potentiation of the rewarding effect of the self-administered drug. The aim of the present study was to examine whether MPEP has intrinsic positive reinforcing and rewarding effects. In experiment 1, rats were trained to self-administer either ketamine [0.5 mg/kg/infusion, 2 h sessions, fixed-ratio (FR) 3] or heroin (0.05 mg/kg/infusion, 1 h sessions, FR 10), followed by a number of substitution sessions with MPEP (1 mg/kg/infusion) or saline. In experiment 2, drug-naïve rats were allowed to acquire intravenous self-administration of MPEP (1 mg/kg/infusion, 2 h sessions, FR 3) or saline. In experiment 3, rats were subjected to a single-trial unbiased conditioned place preference protocol with MPEP (0.3-10 mg/kg i.v., 20 min conditioning). It was found that (1) substitution with MPEP in rats which had learned to self-administer ketamine or heroin resulted in stable self-administration behavior, whereas substitution with saline resulted in a typical extinction profile, (2) drug-naïve rats learned to self-administer MPEP, but not saline, and self-administration remained stable for at least 7 sessions, and (3) MPEP induced dose-dependent place preference with a minimal effective dose of 3 mg/kg. These data clearly demonstrate that MPEP has (weak) positive reinforcing and rewarding effects when administered i.v.
Collapse
Affiliation(s)
- Elizabeth L van der Kam
- Solvay Pharmaceuticals, Clinical Candidate Selection, CJ van Houtenlaan 36, Building WWA-D003, 1381 CP Weesp, The Netherlands.
| | | | | |
Collapse
|
38
|
2-Methyl-6(phenylethynyl)-pyridine (MPEP) potentiates ketamine and heroin reward as assessed by acquisition, extinction, and reinstatement of conditioned place preference in the rat. Eur J Pharmacol 2009; 606:94-101. [DOI: 10.1016/j.ejphar.2008.12.042] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 12/09/2008] [Accepted: 12/23/2008] [Indexed: 11/17/2022]
|
39
|
Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
Collapse
Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
| |
Collapse
|