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Schwarting RKW, Wöhr M, Engler H, Sungur AÖ, Schedlowski M. Behaviorally conditioned effects of psychoactive drugs in experimental animals: What we have learned from nearly a century of research and what remains to be learned. Neurosci Biobehav Rev 2024; 162:105721. [PMID: 38754716 DOI: 10.1016/j.neubiorev.2024.105721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 04/26/2024] [Accepted: 05/10/2024] [Indexed: 05/18/2024]
Abstract
Continuous treatment with drugs is a crucial requirement for managing various clinical conditions, including chronic pain and neuropsychiatric disorders such as depression or schizophrenia. Associative learning processes, i.e. Pavlovian conditioning, can play an important role for the effects of drugs and could open new avenues for optimizing patient treatment. In this narrative literature review, we summarize available data in experimental animals regarding the behaviorally conditioned effects of psychostimulants such as d-amphetamine and cocaine, the dopamine receptor agonist apomorphine, the dopamine receptor antagonist haloperidol, morphine and antidepressant drugs. In each section, the drug under discussion is briefly introduced, followed by a detailed examination of conditioning features, including doses and dosing regimens, characteristics of the conditioning process such as test environments or specific conditioned stimuli, testing and conditioned response characteristics, possible extinction or reconditioning or reversal training, neural mechanisms, and finally, the potential clinical relevance of the research area related to the drug. We focus on key outcomes, delve into methodical issues, identify gaps in current knowledge, and suggest future research directions.
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Affiliation(s)
- Rainer K W Schwarting
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany
| | - Markus Wöhr
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany; KU Leuven, Faculty of Psychology and Educational Sciences, Research Unit Brain and Cognition, Laboratory of Biological Psychology, Social and Affective Neuroscience Research Group, Leuven B-3000, Belgium; KU Leuven, Leuven Brain Institute, Leuven B-3000, Belgium
| | - Harald Engler
- Institute of Medical Psychology and Behavioral Immunobiology, Center for Translational Neuro-, and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen D-45147, Germany
| | - A Özge Sungur
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany; KU Leuven, Faculty of Psychology and Educational Sciences, Research Unit Brain and Cognition, Laboratory of Biological Psychology, Social and Affective Neuroscience Research Group, Leuven B-3000, Belgium; KU Leuven, Leuven Brain Institute, Leuven B-3000, Belgium
| | - Manfred Schedlowski
- Institute of Medical Psychology and Behavioral Immunobiology, Center for Translational Neuro-, and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen D-45147, Germany; Department of Clinical Neuroscience, Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm 171 77, Sweden
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Vörös D, Kiss O, Taigiszer M, László BR, Ollmann T, Péczely L, Zagorácz O, Kertes E, Kállai V, Berta B, Kovács A, Karádi Z, Lénárd L, László K. The role of intraamygdaloid oxytocin in spatial learning and avoidance learning. Peptides 2024; 175:171169. [PMID: 38340898 DOI: 10.1016/j.peptides.2024.171169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/26/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
The goal of the present study is to investigate the role of intraamygdaloid oxytocin in learning-related mechanisms. Oxytocin is a neuropeptide which is involved in social bonding, trust, emotional responses and various social behaviors. By conducting passive avoidance and Morris water maze tests on male Wistar rats, the role of intraamygdaloid oxytocin in memory performance and learning was investigated. Oxytocin doses of 10 ng and 100 ng were injected into the central nucleus of the amygdala. Our results showed that 10 ng oxytocin significantly reduced the time required to locate the platform during the Morris water maze test while significantly increasing the latency time in the passive avoidance test. However, the 100 ng oxytocin experiment failed to produce a significant effect in either of the tests. Wistar rats pretreated with 20 ng oxytocin receptor antagonist (L-2540) were administered 10 ng of oxytocin into the central nucleus of the amygdala and were also subjected to the aforementioned tests to highlight the role of oxytocin receptors in spatial- and avoidance learning. Results suggest that oxytocin supports memory processing during both the passive avoidance and the Morris water maze tests. Oxytocin antagonists can however block the effects of oxytocin in both tests. The results substantiate that oxytocin uses oxytocin receptors to enhance memory and learning performance.
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Affiliation(s)
- Dávid Vörös
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Orsolya Kiss
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Márton Taigiszer
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Bettina Réka László
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary
| | - Tamás Ollmann
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - László Péczely
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Olga Zagorácz
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Erika Kertes
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Veronika Kállai
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Beáta Berta
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Learning in Biological and Artificial Systems Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary
| | - Anita Kovács
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary
| | - Zoltán Karádi
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Cellular Bioimpedance Research Group, Szentágothai Research Center, University of Pécs, 7602 Pécs, Hungary; Molecular Endocrinology and Neurophysiology Research Group, Szentágothai Center, University of Pécs, 7602 Pécs, Hungary
| | - László Lénárd
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary; Molecular Endocrinology and Neurophysiology Research Group, Szentágothai Center, University of Pécs, 7602 Pécs, Hungary
| | - Kristóf László
- Medical School, Institute of Physiology, University of Pécs, Szigeti Str. 12, P.O. Box 99, 7602 Pécs, Hungary; Neuropeptides, Cognition, Animal Models of Neuropsychiatric Disorders Research Group, Medical School, Institute of Physiology, University of Pécs, 7602 Pécs, Hungary; Neuroscience Center, University of Pécs, 7602 Pécs, Hungary.
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Milton AL. Drug memory reconsolidation: from molecular mechanisms to the clinical context. Transl Psychiatry 2023; 13:370. [PMID: 38040677 PMCID: PMC10692359 DOI: 10.1038/s41398-023-02666-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 11/07/2023] [Accepted: 11/13/2023] [Indexed: 12/03/2023] Open
Abstract
Since its rediscovery at the beginning of the 21st Century, memory reconsolidation has been proposed to be a therapeutic target for reducing the impact of emotional memories that can go awry in mental health disorders such as drug addiction (substance use disorder, SUD). Addiction can be conceptualised as a disorder of learning and memory, in which both pavlovian and instrumental learning systems become hijacked into supporting drug-seeking and drug-taking behaviours. The past two decades of research have characterised the details of the molecular pathways supporting the reconsolidation of pavlovian cue-drug memories, with more recent work indicating that the reconsolidation of instrumental drug-seeking memories also relies upon similar mechanisms. This narrative review considers what is known about the mechanisms underlying the reconsolidation of pavlovian and instrumental memories associated with drug use, how these approaches have translated to experimental medicine studies, and the challenges and opportunities for the clinical use of reconsolidation-based therapies.
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Affiliation(s)
- Amy L Milton
- Department of Psychology, University of Cambridge, Cambridge, UK.
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Smith DM, Torregrossa MM. The ventral tegmental area dopamine to lateral amygdala projection supports cocaine cue associative learning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554187. [PMID: 37662292 PMCID: PMC10473658 DOI: 10.1101/2023.08.22.554187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Learning and memory mechanisms are critically involved in drug craving and relapse. Environmental cues paired with repeated drug use acquire incentive value such that exposure to the cues alone can trigger craving and relapse. The amygdala, particularly the lateral amygdala (LA), underlies cue-related learning processes that assign valence to environmental stimuli including drug-paired cues. Evidence suggests that the ventral tegmental area (VTA) dopamine (DA) projection to the LA participates in encoding reinforcing effects that act as a US in conditioned cue reward-seeking as DA released in the amygdala is important for emotional and behavioral functions. Here we used chemogenetics to manipulate these VTA DA inputs to the LA to determine the role of this projection for acquisition of drug-cue associations and reinstatement of drug-seeking. We found inhibiting DA input to the LA during cocaine self-administration slowed acquisition and weakened the ability of the previously cocaine-paired cue to elicit cocaine-seeking. Conversely, exciting the projection during self-administration boosted the salience of the cocaine-paired cue as indicated by enhanced responding during cue-induced reinstatement. Importantly, interfering with DA input to the LA had no impact on the ability of cocaine to elicit a place preference or induce reinstatement in response to a priming cocaine injection. Overall, we show that manipulation of projections underlying DA signaling in the LA may be useful for developing therapeutic interventions for substance use disorders.
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Pantoni MM, Kim JL, Van Alstyne KR, Anagnostaras SG. MDMA and memory, addiction, and depression: dose-effect analysis. Psychopharmacology (Berl) 2022; 239:935-949. [PMID: 35179622 PMCID: PMC8891111 DOI: 10.1007/s00213-022-06086-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/07/2022] [Indexed: 12/17/2022]
Abstract
RATIONALE ±3,4-Methylenedioxymethamphetamine (MDMA) is a recreational drug that shows substantial promise as a psychotherapeutic agent. Still, there is some concern regarding its behavioral toxicity, and its dose-effect relationship is poorly understood. We previously explored the role of dose in the cognitive effects of MDMA in a systematic review of existing literature and found no evidence in animals that MDMA impairs memory at low doses (< 3 mg/kg) but mixed results at high doses (≥ 3 mg/kg). Since this review comprised mostly of single-dose studies and an assortment of methodologies, an empirical dose-ranging study on this topic is warranted. OBJECTIVES The current study aims to evaluate the conclusion from our systematic review that 3 mg/kg may be the threshold for MDMA-induced amnesia, and to further understand the dose-effect relationship of MDMA on behavioral assays of memory, addiction, and depression. METHODS We systematically examined the effects of 0.01 to 10 mg/kg MDMA on Pavlovian fear conditioning; behavioral sensitization, conditioned place preference, and conditioned responding; and the Porsolt forced swim test in mice. RESULTS High doses of MDMA (≥ 3 mg/kg) produced amnesia of fear conditioning memory, some evidence of an addictive potential, and antidepressant effects, while low doses of MDMA (≤ 1 mg/kg) had no effect on these behaviors. CONCLUSIONS The present dose-ranging study provides further evidence that 3 mg/kg is the threshold for MDMA-induced amnesia. These findings, in addition to our systematic review, demonstrate that careful selection of MDMA dose is critical. High doses (≥ 3 mg/kg) should likely be avoided due to evidence that they can produce amnesia and addiction. Conversely, there is little evidence to suggest that low doses, which are usually administered in clinical studies (approximately 1-2 mg/kg), will lead to these same adverse effects. Ultra-low doses (< 1 mg/kg) are likely even safer and should be investigated for therapeutic effects in future studies.
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Affiliation(s)
- Madeline M. Pantoni
- grid.266100.30000 0001 2107 4242Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA USA ,grid.266102.10000 0001 2297 6811Translational Psychedelic Research Program, Department of Psychiatry and Behavioral Sciences, University of California San Francisco, CA San Francisco, USA
| | - Jinah L. Kim
- grid.266100.30000 0001 2107 4242Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA USA
| | - Kaitlin R. Van Alstyne
- grid.266100.30000 0001 2107 4242Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA USA
| | - Stephan G. Anagnostaras
- grid.266100.30000 0001 2107 4242Molecular Cognition Laboratory, Department of Psychology, University of California San Diego, La Jolla, CA USA ,grid.266100.30000 0001 2107 4242Molecular Cognition Laboratory, Program in Neurosciences, University of California San Diego, La Jolla, CA USA
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Servonnet A, Hernandez G, El Hage C, Rompré PP, Samaha AN. Optogenetic Activation of the Basolateral Amygdala Promotes Both Appetitive Conditioning and the Instrumental Pursuit of Reward Cues. J Neurosci 2020; 40:1732-1743. [PMID: 31953370 PMCID: PMC7046336 DOI: 10.1523/jneurosci.2196-19.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 01/10/2023] Open
Abstract
Reward-associated stimuli can both evoke conditioned responses and acquire reinforcing properties in their own right, becoming avidly pursued. Such conditioned stimuli (CS) can guide reward-seeking behavior in adaptive (e.g., locating food) and maladaptive (e.g., binge eating) ways. The basolateral amygdala (BLA) regulates conditioned responses evoked by appetitive CS, but less is known about how the BLA contributes to the instrumental pursuit of CS. Here we studied the influence of BLA neuron activity on both behavioral effects. Water-restricted male rats learned to associate a light-tone cue (CS) with water delivery into a port. During these Pavlovian conditioning sessions, we paired CS presentations with photo-stimulation of channelrhodopsin-2 (ChR2)-expressing BLA neurons. BLA photo-stimulation potentiated CS-evoked port entries during conditioning, indicating enhanced conditioned approach and appetitive conditioning. Next, new rats received Pavlovian conditioning without photo-stimulation. These rats then received instrumental conditioning sessions where they could press an inactive lever or an active lever that produced CS presentation, without water delivery. Rats pressed more on the active versus inactive lever, and pairing CS presentation with BLA-ChR2 photo-stimulation intensified responding for the CS. This suggests that BLA-ChR2 photo-stimulation enhanced CS incentive value. In a separate experiment, rats did not reliably self-administer BLA-ChR2 stimulations, suggesting that BLA neurons do not carry a primary reward signal. Last, intra-BLA infusions of d-amphetamine also intensified lever-pressing for the CS. The findings suggest that BLA-mediated activity facilitates CS control over behavior by enhancing both appetitive Pavlovian conditioning and instrumental pursuit of CS.SIGNIFICANCE STATEMENT Cues paired with rewards can guide animals to valuable resources such as food. Cues can also promote dysfunctional reward-seeking behavior, as in overeating. Reward-paired cues influence reward seeking through two major mechanisms. First, reward-paired cues evoke conditioned anticipatory behaviors to prepare for impending rewards. Second, reward-paired cues are powerful motivators and they can evoke pursuit in their own right. Here we show that increasing neural activity in the basolateral amygdala enhances both conditioned anticipatory behaviors and pursuit of reward-paired cues. The basolateral amygdala therefore facilitates cue-induced control over behavior by both increasing anticipation of impending rewards and making reward cues more attractive.
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Affiliation(s)
| | - Giovanni Hernandez
- Department of Neurosciences
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal H4H 1R3, Quebec, Canada
| | | | | | - Anne-Noël Samaha
- Department of Pharmacology and Physiology,
- Groupe de recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, Montreal H3T 1J4, Quebec, Canada, and
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Yu YJ, Huang CH, Chang CH, Gean PW. Involvement of protein phosphatases in the destabilization of methamphetamine-associated contextual memory. ACTA ACUST UNITED AC 2016; 23:486-93. [PMID: 27531839 PMCID: PMC4986857 DOI: 10.1101/lm.039941.115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 07/08/2016] [Indexed: 01/20/2023]
Abstract
Destabilization refers to a memory that becomes unstable when reactivated and is susceptible to disruption by amnestic agents. Here we delineated the cellular mechanism underlying the destabilization of drug memory. Mice were conditioned with methamphetamine (MeAM) for 3 d, and drug memory was assessed with a conditioned place preference (CPP) protocol. Anisomycin (ANI) was administered 60 min after the CPP retrieval to disrupt reconsolidation. We found that destabilization of MeAM CPP after the application of ANI was blocked by the N-methyl-d-aspartate receptor (NMDAR) antagonist MK-801 and the NR2B antagonist ifenprodil (IFN) but not by the NR2A antagonist NVP-AAM077 (NVP). In addition, decrease in the phosphorylation of GluR1 at Serine845 (p-GluR1-Ser845), decrease in spine density, and a reduction in the AMPAR/NMDAR ratio in the basolateral amygdala (BLA) were reversed after the MK-801 treatment. The effect of ANI on destabilization was prevented by the protein phosphatase 2B (calcineurin, CaN) inhibitors cyclosporine A (CsA) and FK-506 and the protein phosphatase 1 (PP1) inhibitors calyculin A (CA) and okadaic acid (OA). These results suggest that memory destabilization involves the activation of NR2B-containing NMDARs, which in turn allows the influx of Ca2+. Increased intracellular Ca2+ stimulates CaN, leading to the dephosphorylation and inactivation of inhibitor 1 and the activation of PP1. PP1 then dephosphorylates p-GluR1-Ser845 to elicit AMPA receptor (AMPAR) endocytosis and destabilization of the drug memory.
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Affiliation(s)
- Yang-Jung Yu
- Institute of Basic Medical Sciences and Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan 701
| | - Chien-Hsuan Huang
- Institute of Basic Medical Sciences and Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan 701
| | - Chih-Hua Chang
- Institute of Basic Medical Sciences and Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan 701
| | - Po-Wu Gean
- Institute of Basic Medical Sciences and Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan 701
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Hou B. Effects of the κ-opioid receptor on the inhibition of 100 Hz electroacupuncture on cocaine-induced conditioned place preference. Exp Ther Med 2016; 12:1604-1610. [PMID: 27588082 DOI: 10.3892/etm.2016.3504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 04/08/2016] [Indexed: 12/25/2022] Open
Abstract
The administration of 100 Hz electroacupuncture has been demonstrated to suppress cocaine-induced conditioned place preference (CPP) in rats, and there is evidence that the κ-opioid receptor may have a role in cocaine addiction. The present study sought to explore the mechanisms underlying the inhibitory effects of 100 Hz electroacupuncture on cocaine-induced CPP in rats. A rat model of cocaine-induced CPP was used in the present study to investigate the following: i) Naloxone treatment (5 and 10 mg/kg) following 100 Hz electroacupuncture-mediated inhibition on cocaine-induced CPP, revealing that a high dose (10 mg/kg) of naloxone blocked the inhibitory effects of 100 Hz electroacupuncture on cocaine-induced CPP; ii) nor-binaltorphimine (nor-BNI) on 100 Hz electroacupuncture-mediated inhibition on cocaine-induced CPP, which indicated that administration of 10 µg/5 µl and 0.3 µg/1 µl nor-BNI intracerebroventricularly and via the nucleus accumbens, respectively, reversed the inhibitory effects of 100 Hz electroacupuncture on cocaine-induced CPP, and that injection of nor-BNI in different brain areas of rats blocks the inhibitory effects of electroacupuncture on cocaine-induced CPP; and iv) 100 Hz electroacupuncture on the mRNA expression levels of the κ-opioid receptor in the rat nucleus accumbens and amygdala, which established that mRNA expression levels of κ-opioid receptor in the nucleus accumbens were increased with 100 Hz electroacupuncture plus cocaine-induced CPP. Overall, the results of the present study indicated that 100 Hz electroacupuncture was able to suppress cocaine-induced CPP via the κ-opioid receptor in the nucleus accumbens.
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Affiliation(s)
- Bingjun Hou
- Basic Department, Shandong Medical College, Linyi, Shandong 276000, P.R. China
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Krishnan B. Amygdala-Hippocampal Phospholipase D (PLD) Signaling As Novel Mechanism of Cocaine-Environment Maladaptive Conditioned Responses. Int J Neuropsychopharmacol 2016; 19:pyv139. [PMID: 26802567 PMCID: PMC4926798 DOI: 10.1093/ijnp/pyv139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 12/15/2015] [Accepted: 12/28/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Drug-environment associative memory mechanisms and the resulting conditioned behaviors are key contributors in relapse to cocaine dependence. Recently, we reported rat amygdala phospholipase D as a key convergent downstream signaling partner in the expression of cocaine-conditioned behaviors mediated by glutamatergic and dopaminergic pathways. In the present study, 1 of the 2 known upstream serotonergic targets of phospholipase D, the serotonin (5-hydroxytryptamine) 2C receptor, was investigated for its role in recruiting phospholipase D signaling in cocaine-conditioned behaviors altered in the rat amygdala and dorsal hippocampus. METHODS Using Western-blot analysis, amygdala phospholipase D phosphorylation and total expression of phospholipase D/5-hydroxytryptamine 2C receptor were observed in early (Day-1) and late (Day-14) withdrawal (cocaine-free) states among male Sprague-Dawley rats subjected to 7-day cocaine-conditioned hyperactivity training. Functional studies were conducted using Chinese Hamster Ovary cells with stably transfected human unedited isoform of 5-hydroxytryptamine 2C receptor. RESULTS Phosphorylation of phospholipase D isoforms was altered in the Day-1 group of cocaine-conditioned animals, while increased amygdala and decreased dorsal hippocampus phospholipase D/5-hydroxytryptamine 2C receptor protein expression were observed in the Day-14 cocaine-conditioned rats. Functional cellular studies established that increased p phospholipase D is a mechanistic response to 5-HT2CR activation and provided the first evidence of a biased agonism by specific 5-hydroxytryptamine 2C receptor agonist, WAY163909 in phospholipase D phosphorylation 2, but not phospholipase D phosphorylation 1 activation. CONCLUSIONS Phospholipase D signaling, activated by dopaminergic, glutamatergic, and serotonergic signaling, can be a common downstream element recruited in associative memory mechanisms altered by cocaine, where increased expression in amygdala and decreased expression in dorsal hippocampus may result in altered anxiety states and increased locomotor responses, respectively.
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Lamprecht R. The Role of Actin Cytoskeleton in Memory Formation in Amygdala. Front Mol Neurosci 2016; 9:23. [PMID: 27065800 PMCID: PMC4815361 DOI: 10.3389/fnmol.2016.00023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 03/21/2016] [Indexed: 11/13/2022] Open
Abstract
The central, lateral and basolateral amygdala (BLA) nuclei are essential for the formation of long-term memories including emotional and drug-related memories. Studying cellular and molecular mechanisms of memory in amygdala may lead to better understanding of how memory is formed and of fear and addiction-related disorders. A challenge is to identify molecules activated by learning that subserve cellular changes needed for memory formation and maintenance in amygdala. Recent studies show that activation of synaptic receptors during fear and drug-related learning leads to alteration in actin cytoskeleton dynamics and structure in amygdala. Such changes in actin cytoskeleton in amygdala are essential for fear and drug-related memories formation. Moreover, the actin cytoskeleton subserves, after learning, changes in neuronal morphogenesis and glutamate receptors trafficking in amygdala. These cellular events are involved in fear and drug-related memories formation. Actin polymerization is also needed for the maintenance of drug-associated memories in amygdala. Thus, the actin cytoskeleton is a key mediator between receptor activation during learning and cellular changes subserving long-term memory (LTM) in amygdala. The actin cytoskeleton may serve as a target for pharmacological treatment of fear memory associated with fear and anxiety disorders and drug addiction to prevent the debilitating consequences of these diseases.
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Perathoner S, Cordero-Maldonado ML, Crawford AD. Potential of zebrafish as a model for exploring the role of the amygdala in emotional memory and motivational behavior. J Neurosci Res 2016; 94:445-62. [DOI: 10.1002/jnr.23712] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 01/18/2023]
Affiliation(s)
- Simon Perathoner
- Luxembourg Centre for Systems Biomedicine (LCSB); University of Luxembourg; Belvaux Luxembourg
| | | | - Alexander D. Crawford
- Luxembourg Centre for Systems Biomedicine (LCSB); University of Luxembourg; Belvaux Luxembourg
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12
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Interactions between ethanol and the endocannabinoid system at GABAergic synapses on basolateral amygdala principal neurons. Alcohol 2015; 49:781-94. [PMID: 26603632 DOI: 10.1016/j.alcohol.2015.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/11/2015] [Accepted: 08/25/2015] [Indexed: 12/30/2022]
Abstract
The basolateral amygdala (BLA) plays crucial roles in stimulus value coding, as well as drug and alcohol dependence. Ethanol alters synaptic transmission in the BLA, while endocannabinoids (eCBs) produce presynaptic depression at BLA synapses. Recent studies suggest interactions between ethanol and eCBs that have important consequences for alcohol drinking behavior. To determine how ethanol and eCBs interact in the BLA, we examined the physiology and pharmacology of GABAergic synapses onto BLA pyramidal neurons in neurons from young rats. Application of ethanol at concentrations relevant to intoxication increased, in both young and adult animals, the frequency of spontaneous and miniature GABAergic inhibitory postsynaptic currents, indicating a presynaptic site of ethanol action. Ethanol did not potentiate sIPSCs during inhibition of adenylyl cyclase while still exerting its effect during inhibition of protein kinase A. Activation of type 1 cannabinoid receptors (CB1) in the BLA inhibited GABAergic transmission via an apparent presynaptic mechanism, and prevented ethanol potentiation. Surprisingly, ethanol potentiation was also prevented by CB1 antagonists/inverse agonists. Brief depolarization of BLA pyramidal neurons suppressed GABAergic transmission (depolarization-induced suppression of inhibition [DSI]), an effect previously shown to be mediated by postsynaptic eCB release and presynaptic CB1 activation. A CB1-mediated suppression of GABAergic transmission was also produced by combined afferent stimulation at 0.1 Hz (LFS), and postsynaptic loading with the eCB arachidonoyl ethanolamide (AEA). Both DSI and LFS-induced synaptic depression were prevented by ethanol. Our findings indicate antagonistic interactions between ethanol and eCB/CB1 modulation at GABAergic BLA synapses that may contribute to eCB roles in ethanol seeking and drinking.
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13
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Lénárd L, Kovács A, Ollmann T, Péczely L, Zagoracz O, Gálosi R, László K. Positive reinforcing effects of RFamide-related peptide-1 in the rat central nucleus of amygdala. Behav Brain Res 2014; 275:101-6. [DOI: 10.1016/j.bbr.2014.08.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/24/2014] [Accepted: 08/26/2014] [Indexed: 12/28/2022]
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14
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Young EJ, Aceti M, Griggs EM, Fuchs RA, Zigmond Z, Rumbaugh G, Miller CA. Selective, retrieval-independent disruption of methamphetamine-associated memory by actin depolymerization. Biol Psychiatry 2014; 75:96-104. [PMID: 24012327 PMCID: PMC4023488 DOI: 10.1016/j.biopsych.2013.07.036] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 07/01/2013] [Accepted: 07/25/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Memories associated with drugs of abuse, such as methamphetamine (METH), increase relapse vulnerability to substance use disorder. There is a growing consensus that memory is supported by structural and functional plasticity driven by F-actin polymerization in postsynaptic dendritic spines at excitatory synapses. However, the mechanisms responsible for the long-term maintenance of memories, after consolidation has occurred, are largely unknown. METHODS Conditioned place preference (n = 112) and context-induced reinstatement of self-administration (n = 19) were used to assess the role of F-actin polymerization and myosin II, a molecular motor that drives memory-promoting dendritic spine actin polymerization, in the maintenance of METH-associated memories and related structural plasticity. RESULTS Memories formed through association with METH but not associations with foot shock or food reward were disrupted by a highly-specific actin cycling inhibitor when infused into the amygdala during the postconsolidation maintenance phase. This selective effect of depolymerization on METH-associated memory was immediate, persistent, and did not depend upon retrieval or strength of the association. Inhibition of non-muscle myosin II also resulted in a disruption of METH-associated memory. CONCLUSIONS Thus, drug-associated memories seem to be actively maintained by a unique form of cycling F-actin driven by myosin II. This finding provides a potential therapeutic approach for the selective treatment of unwanted memories associated with psychiatric disorders that is both selective and does not rely on retrieval of the memory. The results further suggest that memory maintenance depends upon the preservation of polymerized actin.
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Affiliation(s)
- Erica J. Young
- Department of Metabolism & Aging, The Scripps Research Institute, Florida.,Department of Neuroscience, The Scripps Research Institute, Florida
| | | | - Erica M. Griggs
- Department of Metabolism & Aging, The Scripps Research Institute, Florida.,Department of Neuroscience, The Scripps Research Institute, Florida
| | - Rita A. Fuchs
- Department of Psychology, University of North Carolina, Chapel Hill
| | - Zachary Zigmond
- Department of Metabolism & Aging, The Scripps Research Institute, Florida.,Department of Neuroscience, The Scripps Research Institute, Florida
| | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Florida
| | - Courtney A. Miller
- Department of Metabolism & Aging, The Scripps Research Institute, Florida.,Department of Neuroscience, The Scripps Research Institute, Florida.,Correspondence to:
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15
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Luo YX, Xue YX, Shen HW, Lu L. Role of amygdala in drug memory. Neurobiol Learn Mem 2013; 105:159-73. [PMID: 23831499 DOI: 10.1016/j.nlm.2013.06.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/16/2013] [Accepted: 06/25/2013] [Indexed: 12/11/2022]
Abstract
Drug addiction is a chronic brain disorder with the hallmark of a high rate of relapse to compulsive drug seeking and drug taking even after long-term abstinence. Addiction has been considered as an aberrant memory that has been termed "addiction memory." Drug-related memory plays a critical role in the maintenance of learned addictive behaviors and emergence of relapse. Disrupting these long-lasting memories by administering amnestic agents or other manipulations during specific phases of drug memory is a promising strategy for relapse prevention. Recent studies on the processes of drug addiction and relapse have demonstrated that the amygdala is involved in associative drug addiction learning processes. In this review, we focus on preclinical studies that used conditioned place preference and self-administration models to investigate the differential roles of the amygdala in each phase of drug-related memory, including acquisition, consolidation, retrieval, reconsolidation, and extinction. These studies indicate that the amygdala plays a critical role in both cue-associative learning and the expression of cue-induced relapse to drug-seeking behavior.
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Affiliation(s)
- Yi-Xiao Luo
- National Institute on Drug Dependence, Peking University, Beijing 100191, China
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16
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Xi ZX, Li X, Li J, Peng XQ, Song R, Gaál J, Gardner EL. Blockade of dopamine D3 receptors in the nucleus accumbens and central amygdala inhibits incubation of cocaine craving in rats. Addict Biol 2013; 18:665-77. [PMID: 22913325 DOI: 10.1111/j.1369-1600.2012.00486.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cue-induced drug seeking progressively increases over time of withdrawal from drug self-administration in rats, a phenomenon called 'incubation of craving'. The underlying mechanisms have been linked to increased expression of brain-derived neurotrophic factor and GluR2-lacking AMPA receptors in the mesolimbic dopamine (DA) system and also to increased extracellular signal-regulated kinase activation in the central amygdala (CeA). However, it remains unclear whether any DA mechanism is also involved in incubation of craving. Recent research demonstrates that cue-induced cocaine seeking appears to parallel increased DA D3 , but not D1 or D2 , receptor expression in the nucleus accumbens (NAc) of rats over time of withdrawal, suggesting possible involvement of D3 receptors (D3 Rs) in incubation of cocaine craving. Here, we report that systemic or local administration of SB-277011A, a highly selective D3 R antagonist, into the NAc (core and shell) or the CeA, but not the dorsal striatum or basolateral amygdala, significantly inhibits expression of incubation of cocaine craving in rats after 2-30 days of withdrawal from previous cocaine self-administration but had no effect on sucrose-seeking behavior in rats after 10-30 days of withdrawal. These data suggest that DA D3 Rs in both the NAc and the CeA play an important role in incubation of cocaine craving in rats and support the potential utility of D3 R antagonists in the treatment of cocaine addiction.
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Affiliation(s)
- Zheng-Xiong Xi
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
| | - Xia Li
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
| | - Jie Li
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
| | - Xiao-Qing Peng
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
| | - Rui Song
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
| | | | - Eliot L. Gardner
- Intramural Research Program; National Institute on Drug Abuse; Baltimore; MD; USA
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17
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AMPA receptor endocytosis in the amygdala is involved in the disrupted reconsolidation of Methamphetamine-associated contextual memory. Neurobiol Learn Mem 2013; 103:72-81. [DOI: 10.1016/j.nlm.2013.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 03/27/2013] [Accepted: 04/09/2013] [Indexed: 11/24/2022]
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18
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Neurobiological dissociation of retrieval and reconsolidation of cocaine-associated memory. J Neurosci 2013; 33:1271-81a. [PMID: 23325262 DOI: 10.1523/jneurosci.3463-12.2013] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Drug use is provoked by the presentation of drug-associated cues, even following long periods of abstinence. Disruption of these learned associations would therefore limit relapse susceptibility. Drug-associated memories are susceptible to long-term disruption during retrieval and shortly after, during memory reconsolidation. Recent evidence reveals that retrieval and reconsolidation are dependent on β-adrenergic receptor (β-AR) activation. Despite this, whether retrieval and reconsolidation are dependent on identical or distinct neural mechanisms is unknown. The prelimbic medial prefrontal cortex (PL-mPFC) and basolateral amygdala (BLA) have been implicated in the expression and reconsolidation of associative memories. Therefore, we investigated the necessity of β-AR activation within the PL-mPFC and BLA for cocaine-associated memory retrieval and reconsolidation in rats. Before or immediately after a cocaine-induced conditioned place preference (CPP) retrieval trial, β-AR antagonists were infused into the PL-mPFC or BLA, followed by daily testing. PL-mPFC infusions before, but not after, a CPP trial disrupted CPP memory retrieval and induced a persistent deficit in retrieval during subsequent trials. In contrast, BLA β-AR blockade had no effect on initial CPP memory retrieval, but prevented CPP expression during subsequent trials indicative of reconsolidation disruption. Our results reveal a distinct dissociation between the neural mechanisms required for cocaine-associated memory retrieval and reconsolidation. Using patch-clamp electrophysiology, we also show that application of a β-AR antagonist prevents norepinephrine-induced potentiation of PL-mPFC pyramidal cell and γ-aminobutyric-acid (GABA) interneuron excitability. Thus, targeted β-AR blockade could induce long-term deficits in drug-associated memory retrieval by reducing neuronal excitability, providing a novel method of preventing cue-elicited drug seeking and relapse.
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19
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Gass JT, Chandler LJ. The Plasticity of Extinction: Contribution of the Prefrontal Cortex in Treating Addiction through Inhibitory Learning. Front Psychiatry 2013; 4:46. [PMID: 23750137 PMCID: PMC3667556 DOI: 10.3389/fpsyt.2013.00046] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/16/2013] [Indexed: 01/04/2023] Open
Abstract
Theories of drug addiction that incorporate various concepts from the fields of learning and memory have led to the idea that classical and operant conditioning principles underlie the compulsiveness of addictive behaviors. Relapse often results from exposure to drug-associated cues, and the ability to extinguish these conditioned behaviors through inhibitory learning could serve as a potential therapeutic approach for those who suffer from addiction. This review will examine the evidence that extinction learning alters neuronal plasticity in specific brain regions and pathways. In particular, subregions of the prefrontal cortex (PFC) and their projections to other brain regions have been shown to differentially modulate drug-seeking and extinction behavior. Additionally, there is a growing body of research demonstrating that manipulation of neuronal plasticity can alter extinction learning. Therefore, the ability to alter plasticity within areas of the PFC through pharmacological manipulation could facilitate the acquisition of extinction and provide a novel intervention to aid in the extinction of drug-related memories.
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Affiliation(s)
- J T Gass
- Department of Neurosciences, Medical University of South Carolina , Charleston, SC , USA
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20
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Krishnan B, Genzer KM, Pollandt SW, Liu J, Gallagher JP, Shinnick-Gallagher P. Dopamine-induced plasticity, phospholipase D (PLD) activity and cocaine-cue behavior depend on PLD-linked metabotropic glutamate receptors in amygdala. PLoS One 2011; 6:e25639. [PMID: 21980514 PMCID: PMC3181343 DOI: 10.1371/journal.pone.0025639] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 09/08/2011] [Indexed: 01/14/2023] Open
Abstract
Cocaine-cue associations induce synaptic plasticity with long lasting molecular and cellular changes in the amygdala, a site crucial for cue-associated memory mechanisms. The underlying neuroadaptations can include marked alterations in signaling via dopamine (DA) receptors (DRs) and metabotropic glutamate (Glu) receptors (mGluRs). Previously, we reported that DR antagonists blocked forms of synaptic plasticity in amygdala slices of Sprague-Dawley rats withdrawn from repeated cocaine administration. In the present study, we investigated synaptic plasticity induced by exogenous DA and its dependence on mGluR signaling and a potential role for phospholipase D (PLD) as a downstream element linked to mGluR and DR signaling. Utilizing a modified conditioned place preference (CPP) paradigm as a functional behavioral measure, we studied the neurophysiological effects after two-weeks to the last cocaine conditioning. We recorded, electrophysiologically, a DR-induced synaptic potentiation in the basolateral to lateral capsula central amygdala (BLA-lcCeA) synaptic pathway that was blocked by antagonists of group I mGluRs, particularly, the PLD-linked mGluR. In addition, we observed 2–2.5 fold increase in PLD expression and 3.7-fold increase in basal PLD enzyme activity. The enhanced PLD activity could be further stimulated (9.3 fold) by a DA D1-like (D1/5R) receptor agonist, and decreased to control levels by mGluR1 and PLD-linked mGluR antagonists. Diminished CPP was observed by infusion of a PLD-linked mGluR antagonist, PCCG-13, in the amygdala 15 minutes prior to testing, two weeks after the last cocaine injection. These results imply a functional interaction between D1/5Rs, group I mGluRs via PLD in the amygdala synaptic plasticity associated with cocaine-cues.
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MESH Headings
- Amygdala/drug effects
- Amygdala/enzymology
- Amygdala/metabolism
- Amygdala/physiology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Benzazepines/pharmacology
- Cocaine/pharmacology
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Cues
- Cyclopropanes/pharmacology
- Dopamine/pharmacology
- Gene Expression Regulation, Enzymologic/drug effects
- Glycine/analogs & derivatives
- Glycine/pharmacology
- Isoenzymes/metabolism
- Long-Term Potentiation/drug effects
- Male
- Memory/drug effects
- Memory/physiology
- Neuronal Plasticity/drug effects
- Phospholipase D/metabolism
- Raclopride/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D5/agonists
- Receptors, Dopamine D5/metabolism
- Receptors, Metabotropic Glutamate/antagonists & inhibitors
- Receptors, Metabotropic Glutamate/metabolism
- Substance Withdrawal Syndrome/metabolism
- Substance Withdrawal Syndrome/physiopathology
- Synapses/drug effects
- Synapses/metabolism
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- Balaji Krishnan
- Department of Pharmacology and Toxicology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America.
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21
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Schmidt K, Krishnan B, Xia Y, Sun A, Orozco-Cabal L, Pollandt S, Centeno M, Genzer K, Gallagher JP, Shinnick-Gallagher P, Liu J. Cocaine withdrawal reduces group I mGluR-mediated long-term potentiation via decreased GABAergic transmission in the amygdala. Eur J Neurosci 2011; 34:177-89. [PMID: 21749491 DOI: 10.1111/j.1460-9568.2011.07769.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cocaine relapse can occur when cocaine-associated environmental cues induce craving. Conditioned place preference (CPP) is a behavioral paradigm modeling the association between cocaine exposure and environmental cues. The amygdala is involved in cocaine cue associations with the basolateral amygdala (BLA) and central amygdala (CeA) acting differentially in cue-induced relapse. Activation of metabotropic glutamate receptors induces synaptic plasticity, the mechanism of which is thought to underlie learning, memory and drug-cue associations. The goal of this study was to examine the neural alterations in responses to group I metabotropic glutamate receptor (mGluR) agonists in the BLA to lateral capsula of CeA (BLA-CeLc) pathway in slices from rats exposed to cocaine-CPP conditioning and withdrawn for 14 days. mGluR1, but not mGluR5, agonist-induced long-term potentiation (mGluR1-LTP) in the BLA-CeLc pathway was reduced in rats withdrawal from cocaine for 2 and 14 days, and exhibited an altered concentration response to picrotoxin. Cocaine withdrawal also reduced γ-aminobutyric acid (GABA)ergic synaptic inhibition in CeLc neurons. Blocking cannabinoid receptor 1 (CB(1) ) reduced mGluR1-LTP in the saline-treated but not cocaine-withdrawn group. Response to CB(1) but not CB(2) agonist was altered after cocaine. Additionally, increasing endocannabinoid (eCB) levels abolished mGluR1-LTP in the saline but not cocaine-withdrawn group. However, CB(1) and CB(2) protein levels were increased in the amygdala of cocaine-withdrawn rats while mGluR1 and mGluR5 remained unchanged. These data suggested that the mechanisms underlying the diminished mGluR1-LTP in cocaine-withdrawn rats involve an altered GABAergic synaptic inhibition mediated by modulation of downstream eCB signaling. These changes may ultimately result in potentiated responses to environmental cues that would bias behavior toward drug-seeking.
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Affiliation(s)
- Kady Schmidt
- Department of Pharmacology and Toxicology, University of Texas Medical Branch at Galveston, Galveston, TX, USA
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22
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Scott D, Hiroi N. Deconstructing craving: dissociable cortical control of cue reactivity in nicotine addiction. Biol Psychiatry 2011; 69:1052-9. [PMID: 21429478 PMCID: PMC3090477 DOI: 10.1016/j.biopsych.2011.01.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 01/11/2011] [Accepted: 01/27/2011] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cue reactivity, the ability of cues associated with addictive substances to induce seeking and withdrawal, is a major contributor to addiction. Although human imaging studies show that cigarette-associated cues simultaneously activate the insula and the orbitofrontal cortex and evoke craving, how these activities functionally contribute to distinct elements of cue reactivity remains unclear. Moreover, it remains unclear whether the simultaneous activation of these cortical regions reflects coordinated functional connectivity or parallel processing. METHODS We selectively lesioned the insula or orbitofrontal cortex with the excitotoxin ibotenic acid in mice, and their approach to nicotine-associated cues (n = 6-13/group) and avoidance of withdrawal-associated cues (n = 5-12/group) were separately examined in place conditioning paradigms. We additionally tested the role of these two cortical structures in approach to food-associated cues (n = 6-7/group) and avoidance of lithium chloride-associated cues (n = 6-7/group). RESULTS Our data show a double dissociation in which excitotoxic lesions of the insula and orbitofrontal cortex selectively disrupted nicotine-induced cue approach and withdrawal-induced cue avoidance, respectively. These effects were not entirely generalized to approach to food-associated cues or avoidance of lithium chloride-associated cues. CONCLUSIONS Our data provide functional evidence that cue reactivity seen in addiction includes unique neuroanatomically dissociable elements and suggest that the simultaneous activation of these two cortical regions in response to smoking-related cues does not necessarily indicate functional connectivity.
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Affiliation(s)
- Daniel Scott
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461
| | - Noboru Hiroi
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461,Correspondence should be addressed to N.H. (), Dominick P. Purpura Department of Neuroscience, Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Golding 104, 1300 Morris Park Avenue, Bronx, New York 10461., 718-430-3124 (tel), 718-430-3125 (fax),
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23
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Cognitive enhancers for facilitating drug cue extinction: insights from animal models. Pharmacol Biochem Behav 2011; 99:229-44. [PMID: 21295059 DOI: 10.1016/j.pbb.2011.01.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/23/2010] [Accepted: 01/24/2011] [Indexed: 12/30/2022]
Abstract
Given the success of cue exposure (extinction) therapy combined with a cognitive enhancer for reducing anxiety, it is anticipated that this approach will prove more efficacious than exposure therapy alone in preventing relapse in individuals with substance use disorders. Several factors may undermine the efficacy of exposure therapy for substance use disorders, but we suspect that neurocognitive impairments associated with chronic drug use are an important contributing factor. Numerous insights on these issues are gained from research using animal models of addiction. In this review, the relationship between brain sites whose learning, memory and executive functions are impaired by chronic drug use and brain sites that are important for effective drug cue extinction learning is explored first. This is followed by an overview of animal research showing improved treatment outcome for drug addiction (e.g. alcohol, amphetamine, cocaine, heroin) when explicit extinction training is conducted in combination with acute dosing of a cognitive-enhancing drug. The mechanism by which cognitive enhancers are thought to exert their benefits is by facilitating consolidation of drug cue extinction memory after activation of glutamatergic receptors. Based on the encouraging work in animals, factors that may be important for the treatment of drug addiction are considered.
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24
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Kuo CS, Chai SC, Chen HH. Mediodorsal nucleus of the thalamus is critical for the expression of memory of methamphetamine-produced conditioned place preference in rats. Neuroscience 2011; 178:138-46. [PMID: 21256933 DOI: 10.1016/j.neuroscience.2010.12.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 12/07/2010] [Accepted: 12/16/2010] [Indexed: 11/20/2022]
Abstract
Methamphetamine (MA) is a powerful and highly addictive psychostimulant. However, the neural substrate mediating MA-induced conditioned effects, an essential part of addiction, remain unclear. The present study investigated the involvement of the anterior cingulate cortex (ACC), the lateral nucleus of amygdala (LNA), and the mediodorsal nucleus of the thalamus (MD) in MA-conditioned place preference (CPP). Rats underwent bilateral radio-frequency lesions of the ACC, LNA, or MD followed by MA CPP training. Lesions of the MD, but not the ACC or LNA, disrupted MA CPP learning. To clarify the role of the MD on the different stages of the MA CPP memory process, bilateral microinfusions of lidocaine into the MD were performed 5 min prior to each conditioning trial, immediately after the conditioning trial, or 5 min before the testing phase. Pretesting, but not pre- or post-conditioning, infusions of lidocaine into the MD impaired MA CPP. Furthermore, a clear preference for the previously conditioned MA paired cues was expressed when the rats were tested again 24 h after infusions of lidocaine. These results are interpreted as indicating that the MD is specifically involved in the memory retrieval process of MA associated memory which suggests the MD could have an important role in relapse in individuals suffering from MA addiction.
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Affiliation(s)
- C-S Kuo
- Institute of Pharmacology and Toxicology, Tzu Chi University, 701, Section 3, Chung-Yang Road, Hualien, 970 Taiwan, ROC
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25
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McDonald RJ, Yim TT, Lehmann H, Sparks FT, Zelinski EL, Sutherland RJ, Hong NS. Expression of a conditioned place preference or spatial navigation task following muscimol-induced inactivations of the amygdala or dorsal hippocampus: A double dissociation in the retrograde direction. Brain Res Bull 2010; 83:29-37. [DOI: 10.1016/j.brainresbull.2010.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 05/17/2010] [Accepted: 06/02/2010] [Indexed: 11/26/2022]
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26
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Thiel KJ, Wenzel JM, Pentkowski NS, Hobbs RJ, Alleweireldt AT, Neisewander JL. Stimulation of dopamine D2/D3 but not D1 receptors in the central amygdala decreases cocaine-seeking behavior. Behav Brain Res 2010; 214:386-94. [PMID: 20600343 DOI: 10.1016/j.bbr.2010.06.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 05/24/2010] [Accepted: 06/09/2010] [Indexed: 10/19/2022]
Abstract
Alterations in dopamine output within the various subnuclei of the amygdala have previously been implicated in cocaine reinforcement, as well as cocaine-seeking behavior. To elucidate the potential for increased stimulation of D1- and D2-like receptors (D1Rs and D2Rs, respectively) specifically in the central nucleus of the amygdala (CeA) to modulate cue- and cocaine-elicited reinstatement of cocaine-seeking behavior, we infused either the D1R agonist, SKF-38393 (0-4.0 microg/side) or the D2R agonist, 7-OH-DPAT (0-4.0 microg/side) into the CeA immediately prior to tests for cue and cocaine-primed reinstatement. We also examined the effects of 7-OH-DPAT on cocaine self-administration as a positive behavioral control. 7-OH-DPAT decreased cue-and cocaine-primed reinstatement, and reduced the number of cocaine infusions obtained during self-administration; SKF-38393 produced no discernable effects. The results suggest that enhanced stimulation of D2Rs, but not D1Rs, in the CeA is sufficient to inhibit expression of the incentive motivational effects of cocaine priming and cocaine-paired cues. Together with previous findings that D1R blockade attenuates reinstatement of cocaine-seeking behavior, the results suggest that D1R stimulation may be necessary, but not sufficient, to modulate the incentive motivational effects of cues and cocaine priming.
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Affiliation(s)
- Kenneth J Thiel
- Department of Psychology, Arizona State University, P.O. Box 871104, Tempe, AZ 85287-1104, United States
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Buffalari DM, See RE. Amygdala mechanisms of Pavlovian psychostimulant conditioning and relapse. Curr Top Behav Neurosci 2010; 3:73-99. [PMID: 21161750 DOI: 10.1007/7854_2009_18] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Psychostimulant addiction often consists of periods of sustained drug abstinence disrupted by periods of relapse and renewed heavy drug use. Prevention of relapse remains the greatest challenge to the successful treatment of drug addiction. Drug-associated cues are a primary trigger for relapse, as they can elicit intense craving for the drug. These cues become associated with the drug reward through Pavlovian learning processes that develop over multiple drug-cue pairings. The amygdala (AMY) is critical for such drug-related learning. Intrinsic and extrinsic circuitry position the AMY to integrate cue and drug-related information and influence drug-seeking and drug-taking behaviors. Animal models of conditioned drug reward, drug use, and relapse have confirmed the necessary role of the AMY for drug conditioned cues to control motivated behavior. Neurons within the AMY are responsive to the primary effects of psychostimulants, and more critically, they also respond to the presentation of drug-associated cues. The mechanisms by which conditioned cues come to influence drug-seeking behavior likely involve long-term plasticity and neuroadaptations within the AMY. A greater understanding of the associative learning mechanisms that depend upon the AMY and related limbic and cortical structures, and the process by which drug cues come to gain control over behavior that maintains the addictive state, will facilitate the development of more effective addiction treatments.
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Affiliation(s)
- Deanne M Buffalari
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA.
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László K, Tóth K, Kertes E, Péczely L, Lénárd L. The role of neurotensin in positive reinforcement in the rat central nucleus of amygdala. Behav Brain Res 2009; 208:430-5. [PMID: 20035801 DOI: 10.1016/j.bbr.2009.12.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 12/10/2009] [Accepted: 12/12/2009] [Indexed: 10/20/2022]
Abstract
In the central nervous system neurotensin (NT) acts as a neurotransmitter and neuromodulator. It was shown that NT has positive reinforcing effects after its direct microinjection into the ventral tegmental area. The central nucleus of amygdala (CeA), part of the limbic system, plays an important role in learning, memory, regulation of feeding, anxiety and emotional behavior. By means of immunohistochemical and radioimmune methods it was shown that the amygdaloid body is relatively rich in NT immunoreactive elements and NT receptors. The aim of our study was to examine the possible effects of NT on reinforcement and anxiety in the CeA. In conditioned place preference test male Wistar rats were microinjected bilaterally with 100 or 250 ng NT in volume of 0.4 microl or 35 ng neurotensin receptor 1 (NTS1) antagonist SR 48692 alone, or NTS1 antagonist 15 min before 100 ng NT treatment. Hundred or 250 ng NT significantly increased the time rats spent in the treatment quadrant. Prior treatment with the non-peptide NTS1 antagonist blocked the effects of NT. Antagonist itself did not influence the reinforcing effect. In elevated plus maze test we did not find differences among the groups as far as the anxiety index (time spent on the open arms) was concerned. Our results suggest that in the rat ACE NT has positive reinforcing effects. We clarified that NTS1s are involved in this action. It was also shown that NT does not influence anxiety behavior.
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Affiliation(s)
- Kristóf László
- Institute of Physiology, Pécs University Medical School, Pécs, Hungary
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Hall FS, Li XF, Randall-Thompson J, Sora I, Murphy DL, Lesch KP, Caron M, Uhl GR. Cocaine-conditioned locomotion in dopamine transporter, norepinephrine transporter and 5-HT transporter knockout mice. Neuroscience 2009; 162:870-80. [PMID: 19482066 DOI: 10.1016/j.neuroscience.2009.05.058] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/06/2009] [Accepted: 05/26/2009] [Indexed: 01/09/2023]
Abstract
The behavioral effects of cocaine are affected by gene knockout (KO) of the dopamine transporter (DAT), the serotonin transporter (SERT) and the norepinephrine transporter (NET). The relative involvement of each of these transporters varies depending on the particular behavioral response to cocaine considered, as well as on other factors such as genetic background of the subjects. Interestingly, the effects of these gene knockouts on cocaine-induced locomotion are quite different from those on reward assessed in the conditioned place preference paradigm. To further explore the role of these genes in the rewarding effects of cocaine, the ability of five daily injections of cocaine to induce conditioned locomotion was assessed in DAT, SERT and NET KO mice. Cocaine increased locomotor activity acutely during the initial conditioning session in SERT KO and NET KO, but not DAT KO, mice. Surprisingly, locomotor responses in the cocaine-paired subjects diminished over the five conditioning sessions in SERT KO mice, while locomotor responses increased in DAT KO mice, despite the fact that they did not demonstrate any initial locomotor responses to cocaine. Cocaine-induced locomotion was unchanged over the course of conditioning in NET KO mice. In the post-conditioning assessment, conditioned locomotion was not observed in DAT KO mice, and was reduced in SERT KO and NET KO mice. These data reaffirm the central role of dopamine and DAT in the behavioral effects of cocaine. Furthermore, they emphasize the polygenic basis of cocaine-mediated behavior and the non-unitary nature of drug reward mechanisms, particularly in the context of previous studies that have shown normal cocaine-conditioned place preference in DAT KO mice.
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Affiliation(s)
- F S Hall
- Molecular Neurobiology Branch, NIDA-IRP/NIH/DHHS, 333 Cassell Drive, Baltimore, MD 21224, USA
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Li W, Gao YH, Chang M, Peng YL, Yao J, Han RW, Wang R. Neuropeptide S inhibits the acquisition and the expression of conditioned place preference to morphine in mice. Peptides 2009; 30:234-40. [PMID: 18992779 DOI: 10.1016/j.peptides.2008.10.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 09/26/2008] [Accepted: 10/06/2008] [Indexed: 11/25/2022]
Abstract
Neuropeptide S (NPS), a recently identified bioactive peptide, was reported to regulate arousal, anxiety, motoring and feeding behaviors. NPS precursor and NPS receptor mRNA were found in the amygdala, the ventral tegmental area (VTA) and the substantia nigra, the area thought to modulate rewarding properties of drugs. In the present study, we examined the influence of NPS on the rewarding action of morphine, using the unbiased conditioned place preference (CPP) paradigm. Morphine (1, 3 and 6 nmol, i.c.v.) induced a significant place preference. For testing the effect of NPS on the acquisition of morphine CPP, mice were given the combination of NPS and morphine on the conditioning days, and without drug treatment on the followed test day. To study the effect of NPS on the expression of morphine CPP, mice received the treatment of saline/morphine on the conditioning days, and NPS on the test day, 15 min before the placement in the CPP apparatus. Our results showed that NPS (0.3-10 nmol) alone neither induced place preference nor aversion, however, NPS (1 and 3 nmol) blocked the acquisition of CPP induced by 3 nmol morphine, and acquisition of 6 nmol morphine-induced CPP was also reduced by NPS (6 and 10 nmol). Moreover, the expression of CPP induced by 6 nmol morphine was also inhibited by NPS (0.1, 1 and 10 nmol). These results revealed the involvement of NPS in rewarding activities of morphine, and demonstrated the interaction between NPS system and opioid system for the first time.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Applied Organic Chemistry, School of Basic Medical Sciences, Lanzhou University, Lanzhou, PR China
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Abstract
The phenomenology of drug craving has become the focus of much research within addictive disorders because of the belief that desire plays a role in maintaining the addiction. Many of the studies have focused on the activation of neural pathways, particularly within the dopamine system in response to specific events or stimuli. While many of these studies have focused on a particular drug of choice, little has been done across addictive disorders. This article will present and review phenomena that induce drug craving, as well as delineate precise neural pathways which are activated during craving and specific neurobiological markers which are associated with an increased risk for drug craving and other forms of addictive behavior.
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Affiliation(s)
- Jeffrey L Fortuna
- Department of Health Science, California State University, Fullerton, CA 92634, USA
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Lambert G, Karila L, Lowenstein W. Neuro-imagerie et cocaïne : une cartographie de la dépendance ? Presse Med 2008; 37:679-88. [DOI: 10.1016/j.lpm.2007.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Accepted: 08/29/2007] [Indexed: 11/30/2022] Open
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Repeated amphetamine administration induces Fos in prefrontal cortical neurons that project to the lateral hypothalamus but not the nucleus accumbens or basolateral amygdala. Psychopharmacology (Berl) 2008; 197:179-89. [PMID: 18080115 PMCID: PMC2553393 DOI: 10.1007/s00213-007-1021-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 11/09/2007] [Indexed: 02/04/2023]
Abstract
RATIONALE The development of sensitization to amphetamine (AMPH) is dependent on increases in excitatory outflow from the medial prefrontal cortex (mPFC) to subcortical centers. These projections are clearly important for the progressive enhancement of the behavioral response during drug administration that persists through withdrawal. OBJECTIVES The objective of this study was to identify the mPFC subcortical pathway(s) activated by a sensitizing regimen of AMPH. MATERIALS AND METHODS Using retrograde labeling techniques, Fos activation was evaluated in the predominant projection pathways of the mPFC of sensitized rats after a challenge injection of AMPH. RESULTS There was a significant increase in Fos-immunoreactive cells in the mPFC, nucleus accumbens (NAc), basolateral amygdala (BLA), and lateral hypothalamus (LH) of rats treated repeatedly with AMPH when compared to vehicle-treated controls. The mPFC pyramidal neurons that project to the LH but not the NAc or BLA show a significant induction of Fos after repeated AMPH treatment. In addition, we found a dramatic increase in Fos-activated orexin neurons. CONCLUSIONS The LH, a region implicated in natural and drug reward processes, may play a role in the development and persistence of sensitization to repeated AMPH through its connections with the mPFC and possibly through its orexin neurons.
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Chambers RA, Sajdyk TJ, Conroy SK, Lafuze JE, Fitz SD, Shekhar A. Neonatal amygdala lesions: co-occurring impact on social/fear-related behavior and cocaine sensitization in adult rats. Behav Neurosci 2008; 121:1316-27. [PMID: 18085884 DOI: 10.1037/0735-7044.121.6.1316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Neurodevelopmental abnormalities of temporal-limbic structures may underlie both adult psychiatric syndromes and increased addiction vulnerability, leading to high frequencies of "dual diagnosis" disorders. Although the amygdala is implicated in various mental disorders and drug addiction, no studies have explored the impact of early developmental damage to the amygdala on phenotypes relating to mental illness and addictions as co-occurring processes. We tested rats with neonatal amygdala lesions (NAML) vs. SHAM-operated controls in a battery of tests--novel field activity, elevated plus maze (EPM), and social interaction (SI) at baseline and after odor and restraint stress--followed by measures of cocaine sensitization (15 mg/kg vs. saline x 5 days + challenge session 2 weeks later) and remeasurement of SI. NAMLs showed increased novelty-related locomotion, less fear responding in the EPM, and resistance to predator-odor- but not to restraint-induced suppression of SI. NAMLs also had elevated cocaine sensitization profiles, and cocaine history differentially affected subsequent SI in NAMLs compared with SHAMs. NAMLs may provide models for understanding a shared neurobiological basis for and complex interactions among psychiatric symptoms, drug exposure history, and addiction vulnerability.
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Affiliation(s)
- R Andrews Chambers
- Laboratory for Translational Neuroscience of Dual Diagnosis & Development, Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Roles of the nucleus accumbens and amygdala in the acquisition and expression of ethanol-conditioned behavior in mice. J Neurosci 2008; 28:1076-84. [PMID: 18234886 DOI: 10.1523/jneurosci.4520-07.2008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although progress has been made identifying the neural areas underlying the primary reinforcing effects of ethanol, few studies have examined the neural areas mediating ethanol-induced conditioned effects. Previous work using the conditioned place preference (CPP) procedure implicates the ventral tegmental area (VTA) (Bechtholt and Cunningham, 2005), but the downstream neural areas modulating the conditioned rewarding effects of ethanol have not been identified. Although the nucleus accumbens (Acb) and the amygdala (Amy), which both receive dopamine innervation from the VTA, have been implicated in the primary reinforcing effects of ethanol, the roles these areas play in ethanol-conditioned behaviors are unknown. In the present set of experiments, we use the CPP procedure along with selective electrolytic lesions to examine the neural areas underlying the acquisition and expression of ethanol conditioned behavior. In the acquisition experiment, male DBA/2J mice received bilateral lesions of the Acb or Amy before CPP training. In the expression experiments, mice received bilateral lesions of the Acb, Acb shell, Acb core, and Amy, or unilateral lesions of the Amy after training but before testing. Lesions of the Acb and Amy before training disrupted acquisition and expression of ethanol CPP. However, when given after training, only lesions of the Amy disrupted expression, whereas lesions of the Acb core facilitated loss of responding, of ethanol CPP. For the first time, these results demonstrate the role of the Acb and Amy in the acquisition and expression of ethanol-induced conditioned reward.
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Rademacher DJ, Napier TC, Meredith GE. Context modulates the expression of conditioned motor sensitization, cellular activation and synaptophysin immunoreactivity. Eur J Neurosci 2007; 26:2661-8. [PMID: 17970739 PMCID: PMC2131708 DOI: 10.1111/j.1460-9568.2007.05895.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We tested the hypothesis that amphetamine (AMPH)-induced conditioned motor sensitization is accompanied by cellular activation (measured by Fos immunoreactivity) and synaptophysin immunoreactivity in reward-related brain areas. Forty-eight rats were tested for conditioned motor sensitization using a conditioning paradigm that was performed in a three-chambered apparatus. Rats underwent two drug pairings with 1.0 mg/kg AMPH in one outer chamber and, on alternate days, were paired with saline in the other. On the fifth day, relative to the first AMPH treatment, AMPH administration increased motor activity in the AMPH-paired context but not in the saline-paired context. Relative to the first saline treatment, saline on the fifth day produced a conditioned increase in motor activity when given in the chamber previously paired with AMPH, and saline given in the saline-paired context produced a conditioned decrease in motor activity. AMPH administered in the AMPH-paired context increased the density of both Fos and synaptophysin immunoreactivity in the dentate gyrus, cornu ammonis (CA)1, CA3, basolateral amygdala and dorsolateral striatum. This pairing between context and drug increased Fos but not synaptophysin immunoreactivity in the nucleus accumbens core and shell. Saline administered in the AMPH-paired context increased the density of Fos immunoreactivity in the basolateral amygdala and nucleus accumbens core. These data indicate that the basolateral amygdala-nucleus accumbens core pathway is necessary for the context-elicited conditioned motor responses, while the hippocampus encodes the spatial context.
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Affiliation(s)
- David J Rademacher
- Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA.
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Hsu E, Packard MG. Medial prefrontal cortex infusions of bupivacaine or AP-5 block extinction of amphetamine conditioned place preference. Neurobiol Learn Mem 2007; 89:504-12. [PMID: 17905604 DOI: 10.1016/j.nlm.2007.08.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 08/13/2007] [Accepted: 08/15/2007] [Indexed: 11/23/2022]
Abstract
The present experiments used reversible lesion techniques and intra-mPFC infusions of the n-methyl D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphonovaleric acid (AP-5) to examine the role of the mPFC in extinction of an amphetamine conditioned place preference (CPP). Following initial training and testing for an amphetamine (2 mg/kg) CPP, adult male Long-Evans rats were given extinction trials that were identical to training, except in the absence of peripheral amphetamine injections. Immediately prior to each extinction trial, rats received intra-mPFC infusions of the anesthetic drug bupivacaine (0.75% solution/0.5 microl), AP-5 (1.25, 2.5, 5.0 microg/0.5 microl), or saline. Following extinction training, rats were given a second CPP test session. Rats receiving intra-mPFC infusions of saline displayed extinction of CPP behavior. In contrast, intra-mPFC infusions of bupivacaine or AP-5 (2.5, 5.0 microg) blocked CPP extinction. The findings indicate (1) the mPFC mediates extinction of approach behavior to drug-associated environmental contexts, and (2) NMDA receptor blockade within the mPFC is sufficient to block extinction of amphetamine CPP behavior.
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Affiliation(s)
- Emily Hsu
- Department of Psychology, Yale University, New Haven, CT 06520, USA
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Herzig V, Schmidt WJ. Amygdala cannulation alters expression of cocaine conditioned place preference and locomotion in rats. Addict Biol 2007; 12:478-81. [PMID: 17678508 DOI: 10.1111/j.1369-1600.2007.00060.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effect of transient inactivation of the amygdala on expression of cocaine conditioned place preference (CPP) and locomotion was studied. We found that rats with bilateral but not unilateral amygdala cannula placement exhibited increased CPP expression during a vehicle and a cocaine test as well as increased cocaine-induced hyper-locomotion. We discuss the observed effects as being caused by the cannulation per se and we conclude that the applied cannulation produced an increased responsiveness of the amygdala by a yet undetermined mechanism.
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Affiliation(s)
- Volker Herzig
- Zoological Institute, Neuropharmacology, University of Tübingen, Germany.
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Abstract
AIMS This review aims to present and interpret evidence that methamphetamine dependence is associated with disorder of brain function that is required for top-down control of behavior. APPROACH Presented here are findings from brain imaging studies of human research participants with histories of chronic methamphetamine abuse in the context of functional consequences and implications for treatment of their dependence on methamphetamine. FINDINGS Brain imaging studies have revealed differences in the brains of research participants who have used methamphetamine chronically and then abstained from taking the drug, compared with healthy control subjects. These abnormalities are prominent in cortical and limbic systems, and include deficits in markers of dopaminergic and serotonergic neurotransmitter systems, differences in glucose metabolism and deficits in gray matter. These abnormalities accompany cognitive deficits, including evidence of impaired inhibitory control. CONCLUSION Cortical deficits in abstinent methamphetamine abusers can affect a wide range of functions that can be important for success in maintaining drug abstinence. These include but are not limited to modulation of responses to environmental stimuli as well as internal triggers that can lead to craving and relapse. Potential therapies may combine behavioral approaches with medications that can improve cognitive control.
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Affiliation(s)
- Kate Baicy
- Department of Psychiatry and Biobehavioral Science, University of California Los Angeles, Los Angeles, CA, USA
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41
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Graham DL, Hoppenot R, Hendryx A, Self DW. Differential ability of D1 and D2 dopamine receptor agonists to induce and modulate expression and reinstatement of cocaine place preference in rats. Psychopharmacology (Berl) 2007; 191:719-30. [PMID: 16835769 DOI: 10.1007/s00213-006-0473-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 06/09/2006] [Indexed: 11/29/2022]
Abstract
RATIONALE D1-Like agonists are self-administered by drug-naive animals, whereas D2-like agonists reinstate cocaine-seeking behavior, but the rewarding and reinstating effects of D1- and D2-like agonists in pavlovian-based conditioned place preference are equivocal. OBJECTIVE To compare the ability of D1 and D2 agonists to produce conditioned place preference with their modulation of expression and reinstatement of an established cocaine place preference. METHODS Using an unbiased procedure, we measured the place preference induced by the D1 receptor agonist SKF 81297 and the D2/D3 receptor agonist quinpirole in drug-naive or cocaine-exposed rats. The rewarding effects of the D1 agonists SKF 82958, ABT-431, A-77636, and the D2/D3 receptor agonist 7-OH-DPAT were also tested. Additionally, we tested the ability of SKF 81297 and quinpirole to modulate expression and reinstatement of an established cocaine place preference. RESULTS The D1 receptor agonists SKF 81297, SKF 82958, and ABT-431 produced dose-dependent conditioned place preferences, whereas A-77636 produced only place aversion, and the D2/D3 agonists quinpirole and 7-OH-DPAT were without effect in drug naive rats. In cocaine-treated rats, SKF-81297-induced place preference was reduced, whereas quinpirole-induced place preference was revealed. Pretreatment using either D1 or D2/D3 agonists blocked expression of an established cocaine place preference, but only the D1 agonist SKF 81297 and cocaine dose-dependently reinstated an extinguished cocaine place preference, whereas the D2/D3 agonist quinpirole induced place aversion but failed to alter cocaine-induced reinstatement. CONCLUSIONS D1, but not D2/D3, agonists mediate rewarding effects and reinstatement of cocaine place preference, but the reinstating effects differ markedly from self-administration paradigms.
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MESH Headings
- Animals
- Behavior, Addictive/metabolism
- Behavior, Addictive/psychology
- Behavior, Animal/drug effects
- Central Nervous System Stimulants/administration & dosage
- Central Nervous System Stimulants/pharmacology
- Cocaine/administration & dosage
- Cocaine/pharmacology
- Cocaine-Related Disorders/metabolism
- Cocaine-Related Disorders/psychology
- Conditioning, Psychological/drug effects
- Dopamine Agonists/pharmacology
- Dose-Response Relationship, Drug
- Extinction, Psychological
- Male
- Motivation
- Motor Activity/drug effects
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/metabolism
- Receptors, Dopamine D3/agonists
- Receptors, Dopamine D3/metabolism
- Reward
- Self Administration
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Affiliation(s)
- Danielle L Graham
- Department of Psychiatry, The Seay Center for Basic and Applied Research in Psychiatric Illness, The University of Texas Southwestern Medical Center, Dallas, TX 75390-9070, USA
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42
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Gerdjikov TV, Giles AC, Swain SN, Beninger RJ. Nucleus accumbens PKA inhibition blocks acquisition but enhances expression of amphetamine-produced conditioned activity in rats. Psychopharmacology (Berl) 2007; 190:65-72. [PMID: 17047929 DOI: 10.1007/s00213-006-0590-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 09/11/2006] [Indexed: 11/25/2022]
Abstract
RATIONALE The nucleus accumbens (NAc) plays a central role in dopamine-produced reward-related learning. In previous studies, the cyclic adenosine monophosphate-dependent protein kinase (PKA) inhibitor Rp-Cyclic 3',5'-hydrogen phosphorothioate adenosine triethylammonium salt (Rp-cAMPS) blocked the acquisition but not expression of NAc reward-related learning for natural rewards and the acquisition of psychostimulant drug conditioning. OBJECTIVES The current study assessed the role of PKA in the expression of NAc amphetamine (amph)-produced conditioning using conditioned activity (CA). MATERIALS AND METHODS After 5 days of habituation, a test environment was paired with bilateral NAc injections of amph (0.0 or 25.0 micro g) and the PKA inhibitor Rp-cAMPS (0.0, 5.0, 10.0, or 20.0 micro g) over three 60-min conditioning sessions separated by 48 h. To test for effects on expression, some groups received vehicle or amph alone before conditioning sessions and were injected with 0.0, 0.25, 5.0, or 20.0 mug of Rp-cAMPS before the single 60-min test session. RESULTS Amph produced acute increases in locomotion and robust CA. Rp-cAMPS impaired the acquisition of amph-produced CA but not its expression; in fact, it enhanced expression. CONCLUSIONS Results show that PKA inhibition blocks the acquisition but not the expression of amph-produced conditioning.
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Ito R, Robbins TW, McNaughton BL, Everitt BJ. Selective excitotoxic lesions of the hippocampus and basolateral amygdala have dissociable effects on appetitive cue and place conditioning based on path integration in a novel Y-maze procedure. Eur J Neurosci 2006; 23:3071-80. [PMID: 16819997 PMCID: PMC1852059 DOI: 10.1111/j.1460-9568.2006.04883.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The hippocampus and amygdala are thought to be functionally distinct components of different learning and memory systems. This functional dissociation has been particularly apparent in pavlovian fear conditioning, where the integrity of the hippocampus is necessary for contextual conditioning, and of the amygdala for discrete cue conditioning. Their respective roles in appetitive conditioning, however, remain equivocal mainly due to the lack of agreement concerning the operational definition of a 'context'. The present study used a novel procedure to measure appetitive conditioning to spatial context or to a discrete cue. Following selective excitotoxic lesions of the hippocampus (HPC) or basolateral amygdala (BLA), rats were initially trained to acquire discrete CS-sucrose conditioning in a Y-maze apparatus with three topographically identical chambers, the chambers discriminated only on the basis of path integration. The same group of animals then underwent 'place/contextual conditioning' where the CS presented in a chamber assigned as the positive chamber was paired with sucrose, but the same CS presented in either of the other two chambers was not. Thus, spatial context was the only cue that the animal could use to retrieve the value of the CS. HPC lesions impaired the acquisition of conditioned place preference but facilitated the acquisition of cue conditioning, while BLA lesions had the opposite effect, retarding the acquisition of cue conditioning but leaving the acquisition of conditioned place preference intact. Here we provide strong support for the notion that the HPC and BLA subserve complementary and competing roles in appetitive cue and contextual conditioning.
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Affiliation(s)
- Rutsuko Ito
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK.
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Sellings LHL, Clarke PBS. 6-Hydroxydopamine lesions of nucleus accumbens core abolish amphetamine-induced conditioned activity. Synapse 2006; 59:374-7. [PMID: 16463400 DOI: 10.1002/syn.20247] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Environmental cues associated with drug experiences appear to play a critical role in drug dependence. We have previously reported that dopamine-depleting lesions of the nucleus accumbens medial shell inhibit amphetamine-conditioned place preference. Here, we examined the effects of analogous lesions on amphetamine-conditioned locomotor activity. Bilateral core, but not medial shell, lesions attenuated unconditioned locomotion and abolished the conditioned locomotor response. Taken with our previous results, these findings confirm a role for accumbens core in amphetamine-induced locomotor activity and suggest that the role of medial shell DA transmission in conditioned place preference is related to reward processing rather than conditioning in general.
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Affiliation(s)
- Laurie H L Sellings
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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Mattson BJ, Morrell JI. Preference for cocaine- versus pup-associated cues differentially activates neurons expressing either Fos or cocaine- and amphetamine-regulated transcript in lactating, maternal rodents. Neuroscience 2006; 135:315-28. [PMID: 16112474 PMCID: PMC1751484 DOI: 10.1016/j.neuroscience.2005.06.045] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2005] [Revised: 06/13/2005] [Accepted: 06/16/2005] [Indexed: 12/01/2022]
Abstract
We studied the neuronal basis of the motivational response to two powerful but radically different rewards-cocaine and maternal nurturing of pups in the postpartum rat (dam) which is in a unique motivational state. We used a place preference method designed to offer a choice between cues associated with a natural reinforcer (pups) and those associated with a pharmacologic reinforcer (cocaine). Using c-Fos or cocaine- and amphetamine-regulated transcript (CART) immunocytochemistry, we identified the neuronal groups that are activated when the dams expressed a preference for either cues-associated with pups or cues-associated with cocaine. Dams that preferred the cocaine-associated cues had more c-Fos positive neurons in medial prefrontal cortex, nucleus accumbens, and basolateral nucleus of amygdala than pup-associated cue preferring dams or control. Except for the accumbens, there was activation of neurons in these same regions with the pup-associated cue preference. In the nucleus accumbens only CART-immunoreactive (not c-Fos) neurons were activated with pup-cue preference. Notably, the medial preoptic area was the single area where greater activation of neurons was seen with a preference for pup-associated versus cocaine-associated cues. These responses were identified in the absence of the stimuli (cocaine or pups) and are proposed to be, in part, activation of these neurons related to motivational processing. Neither the distribution of neurons responding to pup-associated cue preference nor the demonstration that CART-expressing neurons are responsive to reward-associated cue preference has been previously reported. We hypothesize that the expression of preference for cocaine versus pup-associated cues is made possible by the concerted activity of these regionally distributed networks of neurons that are in part specific to the preference response.
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Affiliation(s)
- B J Mattson
- Rutgers University, Center for Molecular and Behavioral Neuroscience, Newark, NJ 07102, USA.
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See RE. Neural substrates of cocaine-cue associations that trigger relapse. Eur J Pharmacol 2005; 526:140-6. [PMID: 16253228 DOI: 10.1016/j.ejphar.2005.09.034] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 09/23/2005] [Indexed: 11/27/2022]
Abstract
Learned associations that occur during the process of repeated drug use in addiction can later manifest as trigger factors in relapse to renewed drug-seeking and drug-taking behavior. The process of conditioned-cued relapse of drug-seeking behavior has been successfully modeled in animals using the reinstatement procedure, in which chronic drug self-administration can be extinguished or withheld, and then reinstated using conditioned stimuli previously paired with the drug. Our laboratory has extensively studied the neural circuitry underlying conditioned-cued drug-seeking during the expression of reinstatement. In order to study the learning process of drug-cue pairings, we further developed a procedure whereby discrete cocaine-cue pairings can be conducted in a single pavlovian training session in animals previously trained to self-administer cocaine. Presentation of these cues during later reinstatement trials produces robust responding over extinction levels at levels similar to those seen when animals experience the cues on a daily basis. In a series of experiments, we have shown that reversible pharmacological inactivation of the basolateral complex of the amygdala just prior to acquisition of cocaine-cue associations blocks the ability of cocaine-paired stimuli to elicit conditioned-cued reinstatement. This learning process is mediated in part by muscarinic acetylcholine and dopaminergic inputs to the basolateral complex of the amygdala, as intra-amygdala infusion of selective receptor antagonists at the time of acquisition significantly affects reinstatement. We have also recently found that disruption of neural activity within the basolateral complex of the amygdala at the time of consolidation (just after cocaine-cue pairings) will disrupt reinstatement. Taken together, these results reveal the importance of the amygdala in the acquisition, consolidation, and expression of drug-stimulus learning that drives relapse to drug-seeking behavior.
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Affiliation(s)
- Ronald E See
- Department of Neurosciences, 173 Ashley Avenue, BSB 416, Medical University of South Carolina, Charleston, 29425, USA.
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Ito R, Everitt BJ, Robbins TW. The hippocampus and appetitive Pavlovian conditioning: effects of excitotoxic hippocampal lesions on conditioned locomotor activity and autoshaping. Hippocampus 2005; 15:713-21. [PMID: 15906393 DOI: 10.1002/hipo.20094] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hippocampus (HPC) is known to be critically involved in the formation of associations between contextual/spatial stimuli and behaviorally significant events, playing a pivotal role in learning and memory. However, increasing evidence indicates that the HPC is also essential for more basic motivational processes. The amygdala, by contrast, is important for learning about the motivational significance of discrete cues. This study investigated the effects of excitotoxic lesions of the rat HPC and the basolateral amygdala (BLA) on the acquisition of a number of appetitive behaviors known to be dependent on the formation of Pavlovian associations between a reward (food) and discrete stimuli or contexts: (1) conditioned/anticipatory locomotor activity to food delivered in a specific context and (2) autoshaping, where rats learn to show conditioned discriminated approach to a discrete visual CS+. While BLA lesions had minimal effects on conditioned locomotor activity, hippocampal lesions facilitated the development of both conditioned activity to food and autoshaping behavior, suggesting that hippocampal lesions may have increased the incentive motivational properties of food and associated conditioned stimuli, consistent with the hypothesis that the HPC is involved in inhibitory processes in appetitive conditioning.
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Affiliation(s)
- Rutsuko Ito
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB UK.
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Miller CA, Marshall JF. Altered Fos expression in neural pathways underlying cue-elicited drug seeking in the rat. Eur J Neurosci 2005; 21:1385-93. [PMID: 15813948 DOI: 10.1111/j.1460-9568.2005.03974.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cocaine treatment paired with environmental cues establishes a conditioned place preference for that environment. Following expression of this preference, rats show elevated levels of immediate early genes (e.g. c-fos) in the prelimbic cortex (PrL), basolateral amygdala complex (BLC) and nucleus accumbens core (NAcc) compared to drug-unpaired controls. The PrL and BLC are reciprocally connected and both project to the NAcc. Together with the immediate early gene findings, these connections suggest the regions interact as a circuit contributing to cue-elicited drug seeking. To study this circuit, we iontophoresed Fluorogold (FG) into one brain region and assessed colocalization of FG with place preference-induced Fos in the others. Following FG iontophoresis in either the PrL or NAcc, more BLC cells double-labelled for Fos and FG were found in drug-paired than unpaired animals. Following FG iontophoresis in either the BLC or NAcc, no differences were found in the absolute number of PrL Fos/FG cells. This pattern of colocalization suggests that exposure to cocaine-associated cues leads to greater activation of the BLC's efferents to both the PrL and NAcc, while PrL output to the NAcc and BLC is unaffected in IEG expression. These results complement recent findings that suggested attenuated PrL output during place preference expression. Our findings support the view that the BLC, rather than the PrL, provides significant excitatory driving to the NAcc during cue-elicited drug seeking.
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Affiliation(s)
- Courtney A Miller
- Department of Neurobiology and Behaviour, University of California, Irvine, CA 92627-4550, USA
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Abstract
Cocaine treatment paired with environmental cues establishes a conditioned place preference (CPP) for that environment. After expression of this preference, rats show elevated levels of immediate early genes (IEGs; e.g. c-fos) in the prelimbic cortex (PrL), basolateral amygdala complex (BLC), and nucleus accumbens core (NAcc) compared with drug-unpaired controls. These findings, together with the known connections between these regions, suggest that they function as a circuit contributing to cue-elicited craving. To investigate the function of this circuit during drug-seeking, we characterized Fos immunoreactivity of particular neuron classes in each region. To distinguish between IEG activation of GABAergic and non-GABAergic (principally, excitatory projection) neurons, we combined Fos immunohistochemistry with immunohistochemistry for glutamic acid decarboxylase 67 (GAD67) or calcium/calmodulin-dependent protein kinase II (CAMKII) proteins. Within the BLC and NAcc of drug-paired and drug-unpaired animals tested for CPP, we observed no significant differences in the percentage of Fos-immunoreactive (IR) cells that were also GAD67-IR. We also observed no group difference in the degree of Fos/CAMKII overlap in the BLC. However, in PrL, the degree of Fos/GAD67 overlap in the drug-paired group was significantly higher than in the drug-unpaired group. Also, the Fos/CAMKII overlap in the entire PrL as well as just its layer V was significantly lower in the drug-paired animals compared with controls. These findings suggest that, during CPP expression in cocaine-paired animals, the PrL GABAergic interneurons are preferentially activated while PrL output is attenuated, perhaps through greater inhibition of layer V pyramidal neurons. These results suggest a shifting prefrontal cortex cell population response during cocaine-seeking.
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Affiliation(s)
- Courtney A Miller
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697, USA
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Sinha R. Stress and drug abuse. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0921-0709(05)80063-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
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