501
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Shippenberg TS, Zapata A, Chefer VI. Dynorphin and the pathophysiology of drug addiction. Pharmacol Ther 2007; 116:306-21. [PMID: 17868902 PMCID: PMC2939016 DOI: 10.1016/j.pharmthera.2007.06.011] [Citation(s) in RCA: 276] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Accepted: 06/27/2007] [Indexed: 12/30/2022]
Abstract
Drug addiction is a chronic relapsing disease in which drug administration becomes the primary stimulus that drives behavior regardless of the adverse consequence that may ensue. As drug use becomes more compulsive, motivation for natural rewards that normally drive behavior decreases. The discontinuation of drug use is associated with somatic signs of withdrawal, dysphoria, anxiety, and anhedonia. These consequences of drug use are thought to contribute to the maintenance of drug use and to the reinstatement of compulsive drug use that occurs during the early phase of abstinence. Even, however, after prolonged periods of abstinence, 80-90% of human addicts relapse to addiction, suggesting that repeated drug use produces enduring changes in brain circuits that subserve incentive motivation and stimulus-response (habit) learning. A major goal of addiction research is the identification of the neural mechanisms by which drugs of abuse produce these effects. This article will review data showing that the dynorphin/kappa-opioid receptor (KOPr) system serves an essential function in opposing alterations in behavior and brain neurochemistry that occur as a consequence of repeated drug use and that aberrant activity of this system may not only contribute to the dysregulation of behavior that characterizes addiction but to individual differences in vulnerability to the pharmacological actions of cocaine and alcohol. We will provide evidence that the repeated administration of cocaine and alcohol up-regulates the dynorphin/KOPr system and that pharmacological treatments that target this system may prove effective in the treatment of drug addiction.
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Affiliation(s)
- T S Shippenberg
- Integrative Neuroscience Section, NIH/NIDA Intramural Research Program, 333 Cassell Drive, Baltimore, MD 21224, USA.
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502
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Grant JE, Kim SW, Odlaug BL. N-acetyl cysteine, a glutamate-modulating agent, in the treatment of pathological gambling: a pilot study. Biol Psychiatry 2007; 62:652-7. [PMID: 17445781 DOI: 10.1016/j.biopsych.2006.11.021] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Revised: 11/07/2006] [Accepted: 11/23/2006] [Indexed: 11/23/2022]
Abstract
BACKGROUND Although pathological gambling (PG) is relatively common, pharmacotherapy research for PG is limited. N-acetyl cysteine (NAC), an amino acid, seems to restore extracellular glutamate concentration in the nucleus accumbens and therefore offers promise in reducing addictive behavior. METHODS Twenty-seven subjects (12 women) with DSM-IV PG were treated in an 8-week open-label trial of NAC with responders (defined as a > or = 30% reduction in Yale Brown Obsessive Compulsive Scale Modified for Pathological Gambling [PG-YBOCS] total score at end point) randomized to 6 weeks of double-blind NAC or placebo. RESULTS The PG-YBOCS scores decreased from a mean of 20.3 +/- 4.1 at baseline to 11.8 +/- 9.8 at the end of the open-label phase (p < .001). Sixteen of 27 subjects (59.3%) met responder criteria. The mean effective dose of NAC was 1476.9 +/- 311.3 mg/day. Of 16 responders, 13 entered the double-blind phase. Of those assigned to NAC, 83.3% still met responder criteria at the end of the double-blind phase, compared with only 28.6% of those assigned to placebo. CONCLUSIONS The efficacy of NAC lends support to the hypothesis that pharmacological manipulation of the glutamate system might target core symptoms of reward-seeking addictive behaviors such as gambling. Larger, longer, placebo-controlled double-blind studies are warranted.
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Affiliation(s)
- Jon E Grant
- Department of Psychiatry, University of Minnesota School of Medicine, 2450 Riverside Avenue, Minneapolis, MN 55454, USA.
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503
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Torregrossa MM, Kalivas PW. Microdialysis and the neurochemistry of addiction. Pharmacol Biochem Behav 2007; 90:261-72. [PMID: 17928041 DOI: 10.1016/j.pbb.2007.09.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 08/10/2007] [Accepted: 09/04/2007] [Indexed: 10/22/2022]
Abstract
Drug addiction is a process beginning with the initial exposure to a drug of abuse, and leading, in some individuals, to chronic habitual use, and high rates of relapse. Microdialysis allows researchers to monitor the neurochemical changes that occur in the brain after the initial exposure to a drug, and the neurochemical changes that occur with repeated exposure. These changes in the brain are often referred to as drug-induced neuroplasticity, and the aim of this article is to review studies that have utilized microdialysis to increase our understanding of the neuroplasticity that occurs in the process of addiction. We will review how several neurotransmitter systems, including glutamate, GABA, the monoamines, and others, are altered after chronic drug exposure, and how microdialysis can be used to determine if putative treatments for addiction can reverse the drug-induced neuroplasticity in these systems. We will also briefly discuss our recent research using a known change in GABA neurotransmission that occurs during reinstatement of drug-seeking to screen for possible novel treatments to prevent relapse. Overall, microdialysis in combination with other behavioral and pharmacological techniques has greatly increased our understanding of addiction-related neuroplasticity, and provides a means for discovering new ways to prevent these changes and treat addiction.
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Affiliation(s)
- Mary M Torregrossa
- Medical University of South Carolina, Suite 403 Basic Science Building, 173 Ashley Avenue, Charleston, SC 29425, USA.
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504
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Martin-Fardon R, Maurice T, Aujla H, Bowen WD, Weiss F. Differential effects of sigma1 receptor blockade on self-administration and conditioned reinstatement motivated by cocaine vs natural reward. Neuropsychopharmacology 2007; 32:1967-73. [PMID: 17268407 DOI: 10.1038/sj.npp.1301323] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Growing evidence suggests a role for sigma(1) (sigma(1)) receptors in cognitive function, anxiety, depression, regulation of stress responses, and, recently, the appetitive effects of cocaine as measured by conditioned place preference. This study was designed to extend understanding of the role of sigma(1) receptors in addiction-relevant conditioned effects of cocaine by testing the effects of a potent and selective sigma(1) receptor antagonist, BD1047, on conditioned reinstatement of cocaine-seeking. To determine whether modification of conditioned reinstatement by BD1047 is selective for drug-directed behavior or reflects general suppressant effects on motivated behavior, BD1047 was tested also on reinstatement induced by stimuli conditioned to a natural reward, sweetened condensed milk (SCM). Additionally, because sigma(1) receptors have been implicated also in processes linked to the acute reinforcing actions of cocaine, tests of the effects of BD1047 on cocaine self-administration-including a comparison with the sigma(1) antagonist effects on SCM self-administration-were conducted as well. Cocaine self-administering male Wistar rats were trained to associate a discriminative stimulus (S(D)) with the availability of cocaine or SCM, and then subjected to reinstatement tests following extinction of cocaine or SCM-reinforced behavior. BD1047 (1-30 mg/kg) reversed response reinstatement induced by the cocaine S(D) at 20 and 30 mg/kg but did not modify SCM S(D)-induced responding at all but the highest 30 mg dose, at which responding was reversed to extinction levels. BD1047 did not modify responding reinforced directly by SCM or cocaine. The findings support a role for sigma(1) receptors in regulating conditioned responses to cocaine-related contextual stimuli and identify this receptor as a potential treatment target for the prevention of craving and relapse.
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Affiliation(s)
- Rémi Martin-Fardon
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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505
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Cheng RK, Ali YM, Meck WH. Ketamine “unlocks” the reduced clock-speed effects of cocaine following extended training: Evidence for dopamine–glutamate interactions in timing and time perception. Neurobiol Learn Mem 2007; 88:149-59. [PMID: 17513138 DOI: 10.1016/j.nlm.2007.04.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2006] [Revised: 03/26/2007] [Accepted: 04/04/2007] [Indexed: 11/24/2022]
Abstract
The present study examined the clock-speed modulating effects of acute cocaine administration in groups of male rats that received different amounts of baseline training on a 36-s peak-interval procedure prior to initial drug injection. After injection of cocaine (10, 15, or 20mg/kg, ip), rats that had received a minimal amount of training (e.g., <or=30 sessions) prior to drug administration displayed a horizontal leftward shift in their timing functions indicating that the speed of the internal clock was increased. In contrast, rats that had received an extended amount of training (e.g., >or=180 sessions) prior to cocaine (15 mg/kg, ip) administration did not produce this "classic" curve-shift effect, but instead displayed a general disruption of temporal control following drug administration. Importantly, when co-administered with a behaviorally ineffective dose of ketamine (10mg/kg, ip) the ability of cocaine to modulate clock speed in rats receiving extended training was restored. A glutamate "lock/unlock" hypothesis is used to explain the observed dopamine-glutamate interactions as a function of timing behaviors becoming learned habits.
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Affiliation(s)
- Ruey-Kuang Cheng
- Department of Psychology and Neuroscience, Duke University, 572 Research Drive, Genome Sciences Research Building II, Box 91050, Durham, NC 27708, USA
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506
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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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507
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Howell LL, Kimmel HL. Monoamine transporters and psychostimulant addiction. Biochem Pharmacol 2007; 75:196-217. [PMID: 17825265 DOI: 10.1016/j.bcp.2007.08.003] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 07/25/2007] [Accepted: 08/02/2007] [Indexed: 12/27/2022]
Abstract
Psychostimulants are a broadly defined class of drugs that stimulate the central and peripheral nervous systems as their primary pharmacological effect. The abuse liability of psychostimulants is well established and represents a significant public health concern. An extensive literature documents the critical importance of monoamines (dopamine, serotonin and norepinephrine) in the behavioral pharmacology and addictive properties of psychostimulants. In particular, the dopamine transporter plays a primary role in the reinforcing and behavioral-stimulant effects of psychostimulants in animals and humans. Moreover, both serotonin and norepinephrine systems can reliably modulate the neurochemical and behavioral effects of psychostimulants. However, there is a growing body of evidence that highlights complex interactions among additional neurotransmitter systems. Cortical glutamatergic systems provide important regulation of dopamine function, and inhibitory amino acid gamma-aminobutyric acid (GABA) systems can modulate basal dopamine and glutamate release. Repeated exposure to psychostimulants can lead to robust and enduring changes in neurobiological substrates, including monoamines, and corresponding changes in sensitivity to acute drug effects on neurochemistry and behavior. Significant advances in the understanding of neurobiological mechanisms underlying psychostimulant abuse and dependence have guided pharmacological treatment strategies to improve clinical outcome. In particular, functional agonist treatments may be used effectively to stabilize monoamine neurochemistry, influence behavior and lead to long-term abstinence. However, additional clinical studies are required in order to identify safe and efficacious pharmacotherapies.
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Affiliation(s)
- Leonard L Howell
- Division of Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road NE, Atlanta, GA 30329, USA.
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508
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Berglind WJ, See RE, Fuchs RA, Ghee SM, Whitfield TW, Miller SW, McGinty JF. A BDNF infusion into the medial prefrontal cortex suppresses cocaine seeking in rats. Eur J Neurosci 2007; 26:757-66. [PMID: 17651427 DOI: 10.1111/j.1460-9568.2007.05692.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The medial prefrontal cortex (mPFC) is critical for reinstatement of cocaine seeking and is the main source of brain-derived neurotrophic factor (BDNF) to striatal regions of the brain relapse circuitry. To test the hypothesis that BDNF in the mPFC regulates cocaine-seeking behavior, rats were trained to press a lever for cocaine infusions (0.2 mg/inf, 2 h/day) paired with light+tone conditioned stimulus (CS) presentations on 10 consecutive days. After the last self-administration session, rats received a single infusion of BDNF (0.75 microg/0.5 microL/side) into the mPFC; this manipulation produced protracted effects on cocaine-seeking behavior (non-reinforced lever pressing). BDNF pretreatment administered after the last session attenuated cocaine seeking 22 h later and, remarkably, it also blocked cocaine-induced suppression of phospho-extracellular-regulated kinase and elevated BDNF immunoreactivity in the nucleus accumbens. The same pretreatment also suppressed cocaine-seeking behavior elicited by response-contingent CS presentations after 6 days of forced abstinence or extinction training, as well as a cocaine challenge injection (10 mg/kg, i.p.) after extinction training. However, BDNF infused into the mPFC had no effect on food-seeking behavior. Furthermore, BDNF infused on the sixth day of abstinence failed to alter responding, suggesting that the regulatory influence of BDNF is time limited. The suppressive effects of BDNF infused into the mPFC on cocaine seeking indicate that BDNF regulates cortical pathways implicated in relapse to drug seeking and that corticostriatal BDNF adaptations during early abstinence diminish compulsive drug seeking.
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Affiliation(s)
- William J Berglind
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
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509
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Brewer JA, Potenza MN. The neurobiology and genetics of impulse control disorders: relationships to drug addictions. Biochem Pharmacol 2007; 75:63-75. [PMID: 17719013 PMCID: PMC2222549 DOI: 10.1016/j.bcp.2007.06.043] [Citation(s) in RCA: 267] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 06/27/2007] [Accepted: 06/28/2007] [Indexed: 01/28/2023]
Abstract
Impulse control disorders (ICDs), including pathological gambling, trichotillomania, kleptomania and others, have been conceptualized to lie along an impulsive-compulsive spectrum. Recent data have suggested that these disorders may be considered addictions. Here, we review the genetic and neuropathological bases of the impulse control disorders and consider the disorders within these non-mutually exclusive frameworks.
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Affiliation(s)
- Judson A Brewer
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
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510
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Bäckström P, Hyytiä P. Involvement of AMPA/kainate, NMDA, and mGlu5 receptors in the nucleus accumbens core in cue-induced reinstatement of cocaine seeking in rats. Psychopharmacology (Berl) 2007; 192:571-80. [PMID: 17347848 DOI: 10.1007/s00213-007-0753-8] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Accepted: 02/19/2007] [Indexed: 10/23/2022]
Abstract
RATIONALE Nucleus accumbens glutamate transmission has been implicated in drug-seeking behavior, but the involvement of glutamate receptor subtypes in drug seeking maintained by drug-associated cues has not been fully investigated. OBJECTIVE This study examined the effects of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate, N-methyl-D-aspartate (NMDA) and mGlu5 receptor blockade in the nucleus accumbens core on cue-induced reinstatement of cocaine seeking. METHOD Wistar rats were trained to self-administer cocaine and associate a compound stimulus (light and tone) with the drug under an FR4(FR5:S) second-order schedule of reinforcement. After extinction, during which neither cocaine nor the compound stimulus was available, responding was reinstated by contingent presentations of the compound stimulus. The effects of the intra-accumbal AMPA/kainate receptor antagonist 6-cyano-7-nitro-quinoxaline-2, 3-dione (CNQX; 0, 0.01, and 0.03 microg/side), the NMDA antagonist D-2-amino-5-phosphonopentanoate (D-AP5; 0, 1, and 2 microg/side), and the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP; 0, 0.5, and 1 microg/side) on reinstatement were examined in a within-subjects design. RESULTS CNQX and D-AP5 attenuated cue-induced reinstatement of cocaine seeking dose-dependently. MPEP, however, decreased cocaine seeking only relative to baseline because also the saline vehicle included in the within-subjects series of injections decreased responding, possibly reflecting conditioned anhedonic effects of MPEP. In additional experiments, none of the antagonists attenuated locomotor activity or responding for sucrose pellets. CONCLUSIONS The results suggest that cue-induced reinstatement of cocaine seeking after a period of withdrawal from cocaine is sensitive to AMPA/kainate and NMDA receptor antagonism in the nucleus accumbens core and give further evidence for the role of the accumbal glutamate transmission in modulation of drug-seeking behavior.
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MESH Headings
- 2-Amino-5-phosphonovalerate/pharmacology
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Cocaine/administration & dosage
- Cocaine-Related Disorders/physiopathology
- Cocaine-Related Disorders/psychology
- Conditioning, Psychological/drug effects
- Cues
- Dopamine Uptake Inhibitors/administration & dosage
- Dose-Response Relationship, Drug
- Excitatory Amino Acid Antagonists/pharmacology
- Extinction, Psychological/drug effects
- Male
- Motor Activity/drug effects
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiopathology
- Pyridines/pharmacology
- Rats
- Rats, Wistar
- Receptor, Metabotropic Glutamate 5
- Receptors, Kainic Acid/antagonists & inhibitors
- Receptors, Kainic Acid/physiology
- Receptors, Metabotropic Glutamate/antagonists & inhibitors
- Receptors, Metabotropic Glutamate/physiology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Self Administration
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Affiliation(s)
- Pia Bäckström
- Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland
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511
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Knackstedt LA, Kalivas PW. Extended access to cocaine self-administration enhances drug-primed reinstatement but not behavioral sensitization. J Pharmacol Exp Ther 2007; 322:1103-9. [PMID: 17601982 DOI: 10.1124/jpet.107.122861] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cocaine addicts increase the frequency and amount of drug use over time. This characteristic has been modeled by escalating drug intake in rats that were given extended access to cocaine. However, it remains unclear whether the behavior of escalating drug intake or simply increased drug dose is the relevant aspect of this model. The present study investigated whether the phenomenon of escalated drug-taking enhances cocaine-induced sensitization and reinstatement. Rats were trained to self-administer cocaine during daily 1-h sessions for 7 days. A short-access (ShA) group continued to receive 1-h sessions for 10 days while a group of rats was switched to 6 h of drug access, long-access (ShA-LgA) group, for 10 days. In addition, a long-access only (LgA-only) group was added that was not pretrained but was only given extended access for 10 days. ShA subjects maintained stable drug intake; ShA-LgA subjects escalated intake while LgA-only subjects decreased drug intake. All groups displayed an inverted-U shaped cocaine dose-response curve in both the sensitization and reinstatement tests. There was no difference in the expression of behavioral sensitization between groups. Whereas both long-access groups showed reinstatement at more doses of cocaine than the ShA group, the presence of escalation did not affect reinstatement. These results indicate that extended access to cocaine self-administration produces behavioral differences relative to traditional short-access animals in reinstatement, but not sensitization. Furthermore, the differences in reinstatement are predicted more by length of cocaine access than by escalation of drug intake.
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Affiliation(s)
- Lori A Knackstedt
- Department of Neurosciences, Medical University of South Carolina, 173 Ashley Ave, BSB Suite 403, Charleston, SC 29425, USA.
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512
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Edwards S, Graham DL, Bachtell RK, Self DW. Region-specific tolerance to cocaine-regulated cAMP-dependent protein phosphorylation following chronic self-administration. Eur J Neurosci 2007; 25:2201-13. [PMID: 17439498 DOI: 10.1111/j.1460-9568.2007.05473.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chronic cocaine self-administration can produce either tolerance or sensitization to certain cocaine-regulated behaviours, but whether differential alterations develop in the biochemical response to cocaine is less clear. We measured cocaine-induced phosphorylation of multiple cAMP-dependent and -independent protein substrates in mesolimbic dopamine terminal regions following chronic self-administration. Changes in self-administering rats were compared to changes produced by passive yoked injection to identify reinforcement-related regulation, whereas acute and chronic yoked groups were compared to identify the development tolerance or sensitization in the biochemical response to cocaine. Microwave-fixed brain tissue was collected immediately following 4 h of intravenous cocaine administration, and subjected to Western blot analysis of phosphorylated and total protein substrates. Chronic cocaine produced region- and substrate-specific tolerance to cAMP-dependent protein phosphorylation, including GluR1(S845) phosphorylation in striatal and amygdala subregions and NR1(S897) phosphorylation in the CA1 subregion of the hippocampus. Tolerance also developed to cAMP-independent GluR1(S831) phosphorylation in the prefrontal cortex. In contrast, sensitization to presynaptic regulation of synapsin(S9) phosphorylation developed in the hippocampal CA3 subregion while cAMP-dependent tyrosine hydroxylase(S40) phosphorylation decreased in striatal dopamine terminals. Cocaine-induced ERK and CREB(S133) phosphorylation were dissociated in many brain regions and failed to develop either tolerance or sensitization with chronic administration. Positive reinforcement-related correlations between cocaine intake and protein phosphorylation were found only in self-administering animals, while negative dose-related correlations were found primarily with yoked administration. These regional- and substrate-specific adaptations in cocaine-induced protein phosphorylation are discussed in view of their potential impact on the development of cocaine addiction.
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Affiliation(s)
- Scott Edwards
- Department of Psychiatry and the Neuroscience Graduate Program, The Seay Center for Basic and Applied Research in Psychiatric Illness, UT Southwestern Medical Center, Dallas, Texas 75390-9070, USA
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513
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Maldonado C, Rodríguez-Arias M, Castillo A, Aguilar MA, Miñarro J. Effect of memantine and CNQX in the acquisition, expression and reinstatement of cocaine-induced conditioned place preference. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:932-9. [PMID: 17395352 DOI: 10.1016/j.pnpbp.2007.02.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 02/05/2007] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
The present study evaluates the effect of memantine, a non-competitive N-methyl-d-aspartate (NMDA) glutamate receptor antagonist and CNQX, an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor antagonist on the rewarding effects of cocaine in mice, using the conditioned place preference (CPP) paradigm. Cocaine-induced CPP was studied pairing this drug with different memantine or CNQX doses during either the acquisition or the expression phase of the procedure. Once CPP was established, and the preference extinguished, reinstatement was induced by a priming dose of cocaine. Both antagonists, which in themselves do not present motivational actions on the preference shown by the animals, abolished the acquisition and expression of the cocaine-induced CPP. Neither of the antagonists precipitated reinstatement of the preference induced by cocaine but memantine blocked the cocaine-primed reinstatement. Our results suggest that cocaine-induced CPP and reinstatement is largely dependent on glutamate neurotransmission, and confer a putative role for memantine among the tools useful for cocaine management and treatment.
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Affiliation(s)
- C Maldonado
- Unidad de Investigación Psicobiología de las Drogodependencias, Departamento de Psicobiología, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez 21, 46010 Valencia, Spain
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514
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Mato S, Lafourcade M, Robbe D, Bakiri Y, Manzoni OJ. Role of the cyclic-AMP/PKA cascade and of P/Q-type Ca++ channels in endocannabinoid-mediated long-term depression in the nucleus accumbens. Neuropharmacology 2007; 54:87-94. [PMID: 17606273 DOI: 10.1016/j.neuropharm.2007.04.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 04/19/2007] [Accepted: 04/24/2007] [Indexed: 11/24/2022]
Abstract
Glutamate transmission between prefrontal cortex (PFC) and accumbens (NAc) plays a crucial role in the establishment and expression of addictive behaviors. At these synapses exogenous cannabinoid receptor 1 (CB1R) agonists reversibly inhibit excitatory transmission, and the sustained release of endogenous cannabinoids (eCB) following prolonged cortical stimulation leads to long-term depression (LTD). Activation of presynaptic K(+) channels mediates the effects of exocannabinoids, but the transduction pathway underlying the protracted phase of eCB-LTD is unknown. Here we report that the maintenance of eCB-LTD does not involve presynaptic K(+) channels: eCB-LTD was not affected by blockade of K(+) channels with 4-AP (100 microM) and BaCl(2) (300 microM) (fEPSP=78.9+/-5.4% of baseline 58-60 min after tetanus, compared to 78.9+/-5.9% in control slices). In contrast, eCB-LTD was blocked by treatment of the slices with the adenylyl cyclase (AC) activator forskolin (10 microM), and with the protein kinase A (PKA) inhibitor KT5720 (1 microM) (fEPSP=108.9+/-5.7% in forskolin and 110.5+/-7.7% in KT5720, compared to 80.6+/-3.9% in control conditions). Additionally, selective blockade of P/Q-type Ca(2+) channels with omega-agatoxin-IVA (200 nM) occluded the expression of eCB-LTD (fEPSP=113.4+/-15.9% compared to 78.6+/-4.4% in control slices), while blockade of N- with omega-conotoxin-GVIA (1 microM) or L-type Ca(2+) channels with nimodipine (1 microM), was without effect (fEPSP was 83.7+/-5.3% and 87+/-8.9% respectively). These data show that protracted inhibition of AC/PKA activity and P/Q-type Ca(2+) channels are necessary for expression of eCB-LTD at NAc synapses.
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Affiliation(s)
- Susana Mato
- INSERM U862 Equipe Physiopathologie de la Plasticité Synaptique, 146 Rue Léo-Saignat, 33077 Bordeaux Cedex, France
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515
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Corvol JC, Valjent E, Pascoli V, Robin A, Stipanovich A, Luedtke RR, Belluscio L, Girault JA, Hervé D. Quantitative changes in Galphaolf protein levels, but not D1 receptor, alter specifically acute responses to psychostimulants. Neuropsychopharmacology 2007; 32:1109-21. [PMID: 17063155 DOI: 10.1038/sj.npp.1301230] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Striatal dopamine D1 receptors (D1R) are coupled to adenylyl cyclase through Galphaolf. Although this pathway is involved in important brain functions, the consequences of quantitative alterations of its components are not known. We explored the biochemical and behavioral responses to cocaine and D-amphetamine (D-amph) in mice with heterozygous mutations of genes encoding D1R and Galphaolf (Drd1a+/- and Gnal+/-), which express decreased levels of the corresponding proteins in the striatum. Dopamine-stimulated cAMP production in vitro and phosphorylation of AMPA receptor GluR1 subunit in response to D-amph in vivo were decreased in Gnal+/-, but not Drd1a+/- mice. Acute locomotor responses to D1 agonist SKF81259, D-amph and cocaine were altered in Gnal+/- mice, and not in Drd1a+/- mice. This haploinsufficiency showed that Galphaolf but not D1R protein levels are limiting for D1R-mediated biochemical and behavioral responses. Gnal+/- mice developed pronounced locomotor sensitization and conditioned locomotor responses after repeated injections of D-amph (2 mg/kg) or cocaine (20 mg/kg). They also developed normal D-amph-conditioned place preference. The D1R/cAMP pathway remained blunted in repeatedly treated Gnal+/- mice. In contrast, D-amph-induced ERK activation was normal in the striatum of these mice, possibly accounting for the normal development of long-lasting behavioral responses to psychostimulants. Our results clearly dissociate biochemical mechanisms involved in acute and delayed behavioral effects of psychostimulants. They identify striatal levels of Galphaolf as a key factor for acute responses to psychostimulants and suggest that quantitative alterations of its expression may alter specific responses to drugs of abuse, or possibly other behavioral responses linked to dopamine function.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Central Nervous System Stimulants/pharmacology
- Cocaine/pharmacology
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Corpus Striatum/drug effects
- Corpus Striatum/metabolism
- Corpus Striatum/physiopathology
- Cyclic AMP/metabolism
- Dextroamphetamine/pharmacology
- Dopamine/metabolism
- Dopamine Agonists/pharmacology
- Dopamine Uptake Inhibitors/pharmacology
- Extracellular Signal-Regulated MAP Kinases/drug effects
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Female
- GTP-Binding Protein alpha Subunits/genetics
- GTP-Binding Protein alpha Subunits/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Motor Activity/drug effects
- Motor Activity/physiology
- Phosphorylation/drug effects
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptors, AMPA/drug effects
- Receptors, AMPA/metabolism
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D1/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
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516
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Peoples LL, Kravitz AV, Lynch KG, Cavanaugh DJ. Accumbal neurons that are activated during cocaine self-administration are spared from inhibitory effects of repeated cocaine self-administration. Neuropsychopharmacology 2007; 32:1141-58. [PMID: 17019407 DOI: 10.1038/sj.npp.1301203] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hypoactivity of the accumbens is induced by repeated cocaine exposure and is hypothesized to play a role in cocaine addiction. However, it is difficult to understand how a general hypoactivity of the accumbens, which facilitates multiple types of motivated behaviors, could contribute to the selective increase in drug-directed behavior that defines addiction. Electrophysiological recordings, made during sessions in which rats self-administer cocaine, show that most accumbal neurons that encode events related to drug-directed behavior achieve and maintain higher firing rates during the period of cocaine exposure (Task-Activated neurons) than do other accumbal neurons (Task-Non-Activated neurons). We have hypothesized that this difference in activity makes the neurons that facilitate drug-directed behavior less susceptible than other neurons to the chronic inhibitory effects of cocaine. A sparing of neurons that facilitate drug-directed behavior from chronic hypoactivity might lead to a relative increase in the transmission of neuronal signals that facilitate drug-directed behavior through accumbal circuits and thereby contribute to changes in behavior that characterize addiction (ie differential inhibition hypothesis). A prediction of the hypothesis is that neurons that are activated in relation to task events during cocaine self-administration sessions will show less of a decrease in firing across repeated self-administration sessions than will other neurons. To test this prediction, rats were exposed to 30 daily (6 h/day) cocaine self-administration sessions. Chronic extracellular recordings of single accumbal neurons were made during the second to third session and the 30th session. Between-session comparisons showed that decreases in firing were exhibited by Task-Non-Activated, but not by Task-Activated, neurons. During the day 30 session, the magnitude of the difference in firing rate between the two groups of neurons was positively related to the propensity of animals to seek and take cocaine. The findings of the present study are consistent with a basic prediction of the differential inhibition hypothesis and may be relevant to understanding cocaine addiction.
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Affiliation(s)
- Laura L Peoples
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19106, USA.
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517
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Wrase J, Schlagenhauf F, Kienast T, Wüstenberg T, Bermpohl F, Kahnt T, Beck A, Ströhle A, Juckel G, Knutson B, Heinz A. Dysfunction of reward processing correlates with alcohol craving in detoxified alcoholics. Neuroimage 2007; 35:787-94. [PMID: 17291784 DOI: 10.1016/j.neuroimage.2006.11.043] [Citation(s) in RCA: 349] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 11/07/2006] [Accepted: 11/15/2006] [Indexed: 10/23/2022] Open
Abstract
OBJECTIVE Alcohol dependence may be associated with dysfunction of mesolimbic circuitry, such that anticipation of nonalcoholic reward fails to activate the ventral striatum, while alcohol-associated cues continue to activate this region. This may lead alcoholics to crave the pharmacological effects of alcohol to a greater extent than other conventional rewards. The present study investigated neural mechanisms underlying these phenomena. METHODS 16 detoxified male alcoholics and 16 age-matched healthy volunteers participated in two fMRI paradigms. In the first paradigm, alcohol-associated and affectively neutral pictures were presented, whereas in the second paradigm, a monetary incentive delay task (MID) was performed, in which brain activation during anticipation of monetary gain and loss was examined. For both paradigms, we assessed the association of alcohol craving with neural activation to incentive cues. RESULTS Detoxified alcoholics showed reduced activation of the ventral striatum during anticipation of monetary gain relative to healthy controls, despite similar performance. However, alcoholics showed increased ventral striatal activation in response to alcohol-associated cues. Reduced activation in the ventral striatum during expectation of monetary reward, and increased activation during presentation of alcohol cues were correlated with alcohol craving in alcoholics, but not healthy controls. CONCLUSIONS These results suggest that mesolimbic activation in alcoholics is biased towards processing of alcohol cues. This might explain why alcoholics find it particularly difficult to focus on conventional reward cues and engage in alternative rewarding activities.
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Affiliation(s)
- Jana Wrase
- Department of Psychiatry and Psychotherapy, Charité, Universitätsmedizin Berlin, Charité Campus Mitte (CCM), Berlin, Germany
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518
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Mardikian PN, LaRowe SD, Hedden S, Kalivas PW, Malcolm RJ. An open-label trial of N-acetylcysteine for the treatment of cocaine dependence: a pilot study. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:389-94. [PMID: 17113207 DOI: 10.1016/j.pnpbp.2006.10.001] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 09/11/2006] [Accepted: 10/03/2006] [Indexed: 10/23/2022]
Abstract
Recent preclinical studies implicate N-acetylcysteine (NAC), a cysteine prodrug, as a potential medication for preventing relapse to cocaine use; however, little is known about the safety and tolerability of NAC in cocaine-dependent subjects in an outpatient setting. This pilot study examines the safety and tolerability of 3 doses of NAC for the treatment of cocaine dependence. Twenty three treatment-seeking cocaine-dependent patients participated in a 4-week medication trial and received NAC at doses of 1200 mg/day, 2400 mg/day or 3600 mg/day. Results suggested that the three doses were well tolerated. Overall, the retention rates appeared to favor higher doses of NAC (2400 mg/day and 3600 mg/day). The majority of subjects who completed the study (n=16) either terminated use of cocaine completely or significantly reduced their use of cocaine during treatment. Overall the findings suggest that it is feasible to treat cocaine-dependent treatment seekers with N-acetylcysteine on an outpatient basis.
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Affiliation(s)
- Pascale N Mardikian
- Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425, USA.
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519
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Brown TE, Forquer MR, Cocking DL, Jansen HT, Harding JW, Sorg BA. Role of matrix metalloproteinases in the acquisition and reconsolidation of cocaine-induced conditioned place preference. Learn Mem 2007; 14:214-23. [PMID: 17353546 PMCID: PMC1838561 DOI: 10.1101/lm.476207] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Persistent drug seeking/taking behavior involves the consolidation of memory. With each drug use, the memory may be reactivated and reconsolidated to maintain the original memory. During reactivation, the memory may become labile and susceptible to disruption; thus, molecules involved in plasticity should influence acquisition and/or reconsolidation. Recently, matrix metalloproteinases (MMPs) have been shown to influence neuronal plasticity, presumably by their regulation of extracellular matrix (ECM) molecules involved in synaptic reorganization during learning. We hypothesized that inhibition of MMP activity would impair the acquisition and/or reconsolidation of cocaine-conditioned place preference (CPP) in rats. Intracerebral ventricular (i.c.v.) microinjection of a broad spectrum MMP inhibitor, FN-439, prior to cocaine training suppressed acquisition of CPP and attenuated cocaine-primed reinstatement in extinguished animals. In a separate experiment, the cocaine memory was reactivated on two consecutive days with a cocaine priming injection. On these two days, artificial cerebral spinal fluid (aCSF) or FN-439 was administered either 30 min prior to or 1 min after cocaine-primed reinstatement sessions. Infusion of FN-439 partially impaired retrieval of the cocaine-associated context when given 30 min prior to cocaine. In both groups, however, FN-439 suppressed reinstatement compared with controls on the third consecutive test for cocaine-primed reinstatement, when no FN-439 was given. Control experiments demonstrated that two injections of FN-439 + cocaine given in the home cage, or of FN-439 + saline priming injections in the CPP chambers did not disrupt subsequent cocaine-primed reinstatement. These results show for the first time that (1) MMPs play a critical role in acquisition and reconsolidation of cocaine-induced CPP, and (2) rats demonstrate apparent disruption of reconsolidation by an MMP inhibitor after extinction and while they are under the influence of cocaine during reinstatement.
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Affiliation(s)
- Travis E. Brown
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
| | - Melissa R. Forquer
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
| | - Davelle L. Cocking
- Program in Pharmacology/Toxicology, Washington State University, Pullman, Washington 99164-6520, USA
| | - Heiko T. Jansen
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
| | - Joseph W. Harding
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
| | - Barbara A. Sorg
- Alcohol and Drug Abuse Research Program and Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
- Corresponding author.E-mail ; fax (509) 335-4650
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520
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Shin EH, Bian S, Shim YB, Rahman MA, Chung KT, Kim JY, Wang JQ, Choe ES. Cocaine increases endoplasmic reticulum stress protein expression in striatal neurons. Neuroscience 2007; 145:621-30. [PMID: 17303341 DOI: 10.1016/j.neuroscience.2006.12.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Revised: 12/04/2006] [Accepted: 12/05/2006] [Indexed: 11/17/2022]
Abstract
Cocaine administration upregulates the levels of extracellular glutamate and dopamine in the striatum. Activation of the receptors alters calcium homeostasis in striatal neurons leading to the expression of the endoplasmic reticulum (ER) stress proteins. It was therefore hypothesized that cocaine upregulates the expression of the ER stress proteins, immunoglobulin heavy chain binding protein (BiP), Ire1alpha and perk via glutamate and dopamine receptor activation. A novel glutamate microbiosensor and Western immunoblot analyses were mainly performed to test the hypothesis in the rat dorsal striatum. The results showed that i.p. injection of repeated cocaine (20 mg/kg) for nine consecutive days significantly increased extracellular glutamate levels while acute cocaine injection did not. However, the immunoreactivities (IR) of the ER stress proteins in the dorsal striatum were significantly increased by either acute or repeated cocaine injections as compared with saline controls. Intrastriatal injection (i.s.) of the selective group I metabotropic glutamate receptor (mGluR) antagonist N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC; 25 nmol) or the mGluR5 subtype antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP; 2 and 25 nmol) significantly decreased repeated cocaine-induced increases in the IR of the ER stress proteins in the injected dorsal striatum. Similarly, the selective D1 antagonist (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390; 0.1 mg/kg, i.p.) or the N-methyl-d-aspartate antagonist dizocilpine/(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-ibenzo[a,d]cyclohepten-5,10-imine maleate (MK801; 2 nmol, i.s.) decreased acute or repeated cocaine-induced the IR of the ER stress proteins in the dorsal striatum. These data suggest that cocaine upregulates expression of the ER stress proteins in striatal neurons via a mechanism involving activation of glutamate and dopamine receptors.
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MESH Headings
- Animals
- Cocaine/pharmacology
- Cocaine-Related Disorders/metabolism
- Cocaine-Related Disorders/physiopathology
- Corpus Striatum/drug effects
- Corpus Striatum/metabolism
- Dopamine Antagonists/pharmacology
- Dopamine Uptake Inhibitors/pharmacology
- Endoplasmic Reticulum/drug effects
- Endoplasmic Reticulum/metabolism
- Excitatory Amino Acid Antagonists/pharmacology
- Heat-Shock Proteins/drug effects
- Heat-Shock Proteins/metabolism
- Male
- Membrane Proteins/drug effects
- Membrane Proteins/metabolism
- Molecular Chaperones/drug effects
- Molecular Chaperones/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Protein Serine-Threonine Kinases/drug effects
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine D1/drug effects
- Receptors, Dopamine D1/metabolism
- Receptors, Metabotropic Glutamate/drug effects
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Stress, Physiological/chemically induced
- Stress, Physiological/metabolism
- Stress, Physiological/physiopathology
- Up-Regulation/drug effects
- Up-Regulation/physiology
- eIF-2 Kinase/drug effects
- eIF-2 Kinase/metabolism
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Affiliation(s)
- E H Shin
- Department of Biology and Center for Innovative BioPhysio Sensor Technology, Pusan National University, 30 Jangjeon-dong, Kumjeong-gu, C6-311, Pusan 609-735, Korea
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521
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Zieker J, Zieker D, Jatzko A, Dietzsch J, Nieselt K, Schmitt A, Bertsch T, Fassbender K, Spanagel R, Northoff H, Gebicke-Haerter PJ. Differential gene expression in peripheral blood of patients suffering from post-traumatic stress disorder. Mol Psychiatry 2007; 12:116-8. [PMID: 17252001 DOI: 10.1038/sj.mp.4001905] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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522
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Pacchioni AM, Vallone J, Melendez RI, Shih A, Murphy TH, Kalivas PW. Nrf2 gene deletion fails to alter psychostimulant-induced behavior or neurotoxicity. Brain Res 2007; 1127:26-35. [PMID: 17113054 PMCID: PMC1831835 DOI: 10.1016/j.brainres.2006.10.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Revised: 10/12/2006] [Accepted: 10/20/2006] [Indexed: 01/10/2023]
Abstract
The transcription factor NF-E2-related factor (Nrf2) regulates the induction of phase 2 detoxifying enzymes by oxidative stress, including synthesis of the catalytic subunit (xCT) of the heterodimeric cystine-glutamate exchanger (system xc-). Repeated cocaine treatment in rats causes persistent neuroadaptations in glutamate neurotransmission in the nucleus accumbens that result, in part, from reduced activity of system xc-. Since in vitro under- or over-expression of Nrf2 regulates system xc- activity and xCT content, it was hypothesized that in vivo deletion of the Nrf2 gene would: 1) decrease system xc- activity, 2) produce a behavioral phenotype resembling that elicited by chronic cocaine administration, and 3) enhance dopamine depletion after methamphetamine-induced oxidative stress. In all three experiments no genotypic difference was measured between mice sustaining homozygous Nrf2 gene deletion and wild-type littermates. Thus, while Nrf2 is a transcriptional regulator of xCT and capable of protecting cells from oxidative stress, following Nrf2 gene deletion this role can be partially compensated by other mechanisms and methamphetamine-induced oxidative stress and dopamine toxicity does not significantly involve Nrf2.
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Affiliation(s)
- Alejandra M Pacchioni
- Department of Neurosciences, Medical University of South Carolina, 173 Ashley Avenue, BSB 403C, Charleston, SC 29425, USA.
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523
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Giorgi O, Piras G, Corda MG. The psychogenetically selected Roman high- and low-avoidance rat lines: A model to study the individual vulnerability to drug addiction. Neurosci Biobehav Rev 2007; 31:148-63. [PMID: 17164110 DOI: 10.1016/j.neubiorev.2006.07.008] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 07/22/2006] [Indexed: 11/19/2022]
Abstract
The Roman high- (RHA) and low-avoidance (RLA) rat lines were selected for, respectively, rapid vs poor acquisition of two-way active avoidance in the shuttle-box. Here, we review experimental evidence indicating that, compared with their RLA counterparts, RHA rats display a robust sensation/novelty seeking profile, a marked preference and intake of natural or drug rewards, and more pronounced behavioral and neurochemical responses to the acute administration of morphine and psychostimulants. Moreover, we show that (i) the repeated administration of morphine and cocaine elicits behavioral sensitization in RHA, but not RLA, rats, (ii) in sensitized RHA rats, acute morphine and cocaine cause a larger increment in dopamine output in the core, and an attenuated dopaminergic response in the shell of the nucleus accumbens, as compared with RHA rats repeatedly treated with saline, and (iii) such neurochemical changes are not observed in the mesoaccumbens dopaminergic system of the sensitization-resistant RLA line. Behavioral sensitization plays a key role in several cardinal features of addiction, including drug craving, compulsive drug seeking and propensity to relapse following detoxification. Comparative studies in the Roman lines may therefore represent a valid approach to evaluate the contribution of the genotype on the neural substrates of drug sensitization and addiction.
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Affiliation(s)
- Osvaldo Giorgi
- Department of Toxicology, University of Cagliari, Via Ospedale, 72, 09124 Cagliari, Italy.
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524
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Lin SK, Pan WHT, Yeh PH. Prefrontal dopamine efflux during exposure to drug-associated contextual cues in rats with prior repeated methamphetamine. Brain Res Bull 2007; 71:365-71. [PMID: 17208653 DOI: 10.1016/j.brainresbull.2006.10.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 09/29/2006] [Accepted: 10/03/2006] [Indexed: 11/29/2022]
Abstract
Conditioned stimulus-reward response and prefrontal dopamine efflux under context previously paired with methamphetamine administration were assessed in rats with or without prior sensitizing regimen. Sensitizing pretreatment was administered with methamphetamine (1mg/kg, every other day for six sessions) for behavioral sensitization. The animals received methamphetamine (1mg/kg) or saline injection (each for six sessions) to pair with distinct contexts on alternate days to induce conditioned place preference. Then, dopamine outflows in the medial prefrontal cortex were analyzed on the next day via microdialysis study as animals exposed to the methamphetamine or saline-paired context, respectively. Prefrontal DA efflux increased in those rats without sensitizing pretreatment, while they occupied the methamphetamine-paired chamber. The rats with prior sensitizing regimen demonstrated more robust conditioned place preference than those without pretreatment, however, their dopamine efflux was attenuated, while remaining in methamphetamine-paired context. It is suggested that the attenuated responsiveness of mesocortical dopamine transmission in prior sensitized rats may, at least in part, be responsible for their augmented conditioned place preference, which resulted from activation of related brain areas that together strengthen the associative learning to drug-related stimuli. This paradigm may reflect a dysregulated prefrontal function in the methamphetamine abusers.
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Affiliation(s)
- Shi-Kwang Lin
- Institute of Pharmacology, National Yang-Ming University, 155, Section 2 Li-Noon Street, Taipei 112, Taiwan, ROC
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525
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526
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Gallinat J, Kunz D, Lang UE, Neu P, Kassim N, Kienast T, Seifert F, Schubert F, Bajbouj M. Association between cerebral glutamate and human behaviour: the sensation seeking personality trait. Neuroimage 2006; 34:671-8. [PMID: 17123835 DOI: 10.1016/j.neuroimage.2006.10.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 10/06/2006] [Accepted: 10/09/2006] [Indexed: 12/25/2022] Open
Abstract
INTRODUCTION Brain imaging studies have linked the anterior cingulate cortex (ACC) to motivation, drive, and personality traits like novelty and sensation seeking. Animal studies have shown glutamatergic neurotransmission to be important in ACC function as well as motivated behaviour. However, the role of glutamate in related personality traits like sensation seeking has not been investigated in humans. METHODS The associations between sensation seeking personality scores and absolute glutamate concentrations in the ACC and the hippocampal region measured by 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) were investigated. RESULTS ACC glutamate concentration was negatively correlated with the sensation seeking sum score and the experience seeking subscore. A weak negative correlation was also observed between the hippocampal glutamate and the sensation seeking sum score. The reexamination of the glutamate concentration after 4 weeks revealed a similar relationship with sensation seeking. DISCUSSION Although preliminary, the results are in line with the key role of the ACC for motivation and executive control and with the impact of glutamate on novelty related behaviour observed in animal experiments. The role of the hippocampus for novelty processing is discussed. Glutamate measurement with 1H-MRS may facilitate the understanding of biological underpinnings of personality traits and psychiatric diseases associated with dysfunctions in motivation and drive.
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Affiliation(s)
- J Gallinat
- Department of Psychiatry and Psychotherapy, Charité University Medicine Berlin, Campus Mitte, University Hospital of Dresden, Germany.
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527
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Zhang X, Lee TH, Xiong X, Chen Q, Davidson C, Wetsel WC, Ellinwood EH. Methamphetamine induces long-term changes in GABAA receptor alpha2 subunit and GAD67 expression. Biochem Biophys Res Commun 2006; 351:300-5. [PMID: 17056007 DOI: 10.1016/j.bbrc.2006.10.046] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 10/09/2006] [Indexed: 12/24/2022]
Abstract
The present study investigated whether GABA(A) receptor alpha2 subunit and GAD(67) are involved in chronic high dose methamphetamine (METH)-induced sensitization and neurotoxicity. The METH sensitization was established in rats by 7-day pump infusion plus daily injection (25mg/kg/day) and a subsequent 28-day withdrawal period. Behavioral sensitization was assessed by behavioral ratings after challenge with METH (0.5mg/kg). The neurotoxicity was evaluated by the expression of glial fibrillary acidic protein (GFAP). Western blot assay showed that METH sensitization decreases GABA(A) alpha2 subunit and GAD(67) protein levels in the nucleus accumbens (NAc) core and shell, and conversely, these proteins were increased in the caudate. An upregulation of GFAP expression was observed in the caudate, but not in the NAc core and shell. These data suggest that inhibition of GABA transmission in the NAc is related to METH behavioral sensitization, whereas activation of GABA transmission in the caudate is associated with METH-induced neurotoxicity.
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Affiliation(s)
- Xiuwu Zhang
- Department of Psychiatry and Behavioral Science, Duke University Medical Center, Durham, NC 27710, USA.
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528
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Lapish CC, Seamans JK, Chandler LJ. Glutamate-dopamine cotransmission and reward processing in addiction. Alcohol Clin Exp Res 2006; 30:1451-65. [PMID: 16930207 DOI: 10.1111/j.1530-0277.2006.00176.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
While Dale's principle of "one neuron, one neurotransmitter" has undergone revisions to incorporate evidence of the corelease of atypical neurotransmitters such as neuropeptides, the corelease of classical neurotransmitters has only recently been realized. Surprisingly, numerous studies now indicate that the corelease of neurotransmitters in the mammalian central nervous system is not an obscure and rare phenomenon but is widespread and involves most classical neurotransmitters systems. However, the suggestion that glutamate can be coreleased with dopamine (DA) has remained controversial. Furthermore, glutamate-DA cotransmission has not yet been seriously considered in the context of the neurocircuitry of addiction. If glutamate is in fact coreleased with DA as some evidence now suggests, this may have significant implications for advancing our understanding of the interactive role that these 2 neurotransmitters play in cognitive and reward processes. In this commentary, we review the evidence for and against glutamate as a cotransmitter and discuss the potential role of glutamate-DA corelease in addiction. In particular, we describe a recently proposed model in which coreleased glutamate transmits a temporally precise prediction error signal of reward described by Schultz et al., whereas the function of coreleased DA is to exert prolonged modulatory influences on neuronal activity. In addition, we suggest that as alcohol consumption transitions from recreational use to addiction, there is a corresponding transition in the reward valence signal from better than predicted to worse than predicted.
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Affiliation(s)
- Christopher C Lapish
- Department of Neurosciences and the Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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529
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Bossert JM, Gray SM, Lu L, Shaham Y. Activation of group II metabotropic glutamate receptors in the nucleus accumbens shell attenuates context-induced relapse to heroin seeking. Neuropsychopharmacology 2006; 31:2197-209. [PMID: 16341024 PMCID: PMC1570155 DOI: 10.1038/sj.npp.1300977] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Using a rat relapse model, we previously reported that re-exposing rats to a drug-associated context, following extinction of operant responding in a different context, reinstates heroin seeking. In an initial pharmacological characterization, we found that the mGluR2/3 agonist LY379268, which acts centrally to reduce evoked glutamate release, attenuates context-induced reinstatement of heroin seeking when injected systemically or into the ventral tegmental area, the cell body region of the mesolimbic dopamine system. Here, we tested whether injections of LY379268 into the nucleus accumbens (NAc), a terminal region of the mesolimbic dopamine system, would also attenuate context-induced reinstatement of heroin seeking. Rats were trained to self-administer heroin; drug infusions were paired with a discrete tone-light cue. Subsequently, lever pressing was extinguished in the presence of the discrete cue in a context that differed from the drug self-administration context in terms of visual, auditory, tactile, and circadian cues. After extinction of responding, LY379268 was injected to different groups of rats into the NAc core or shell or into the caudate-putamen, a terminal region of the nigrastriatal dopamine system. Injections of LY379268 into the NAc shell (0.3 or 1.0 microg) dose-dependently attenuated context-induced reinstatement of heroin seeking. Injections of 1.0 microg of LY379268 into the NAc core had no effect, while a higher dose (3.0 microg) decreased this reinstatement. Injections of LY379268 (3.0 microg) 1.5 mm dorsal from the NAc core into the caudate-putamen were ineffective. Results suggest an important role of glutamate transmission in the NAc shell in context-induced reinstatement of heroin seeking.
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MESH Headings
- Amino Acids/administration & dosage
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Bridged Bicyclo Compounds, Heterocyclic/administration & dosage
- Conditioning, Operant/drug effects
- Conditioning, Operant/physiology
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Enzyme Activation/physiology
- Extinction, Psychological/drug effects
- Heroin/administration & dosage
- Heroin Dependence/drug therapy
- Heroin Dependence/physiopathology
- Male
- Narcotics/administration & dosage
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiology
- Rats
- Rats, Long-Evans
- Receptors, Metabotropic Glutamate/agonists
- Receptors, Metabotropic Glutamate/physiology
- Secondary Prevention
- Self Administration
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Affiliation(s)
- Jennifer M Bossert
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, Baltimore, MD 21224, USA.
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530
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Camp MC, Mayfield RD, McCracken M, McCracken L, Alcantara AA. Neuroadaptations of Cdk5 in cholinergic interneurons of the nucleus accumbens and prefrontal cortex of inbred alcohol-preferring rats following voluntary alcohol drinking. Alcohol Clin Exp Res 2006; 30:1322-35. [PMID: 16899035 DOI: 10.1111/j.1530-0277.2006.00160.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Neurobiological studies have identified brain areas and related molecular mechanisms involved in alcohol abuse and dependence. Specific cell types in these brain areas and their role in alcohol-related behaviors, however, have not yet been identified. This study examined the involvement of cholinergic cells in inbred alcohol-preferring rats following 1 month of alcohol drinking. Cyclin-dependent kinase 5 (Cdk5) immunoreactivity (IR), a marker of neuronal plasticity, was examined in cholinergic neurons of the nucleus accumbens (NuAcc) and prefrontal cortex (PFC) and other brain areas implicated in alcohol drinking, using dual immunocytochemical (ICC) procedures. Single Cdk5 IR was also examined in several brain areas implicated in alcohol drinking. METHODS The experimental group self-administered alcohol using a 2-bottle-choice test paradigm with unlimited access to 10% (v/v) alcohol and water for 23 h/d for 1 month. An average of 6 g/kg alcohol was consumed daily. Control animals received identical treatment, except that both bottles contained water. Rats were perfused and brain sections were processed for ICC procedures. RESULTS Alcohol drinking resulted in a 51% increase in Cdk5 IR cholinergic interneurons in the shell NuAcc, while in the PFC there was a 51% decrease in the percent of Cdk5 IR cholinergic interneurons in the infralimbic region and a 46% decrease in Cdk5 IR cholinergic interneurons in the prelimbic region. Additionally, single Cdk5 IR revealed a 42% increase in the central nucleus of the amygdala (CNA). CONCLUSIONS This study identified Cdk5 neuroadaptation in cholinergic interneurons of the NuAcc and PFC and in other neurons of the CNA following 1 month of alcohol drinking. These findings contribute to our understanding of the cellular and molecular basis of alcohol drinking and toward the development of improved region and cell-specific pharmacotherapeutic and behavioral treatment programs for alcohol abuse and alcoholism.
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531
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Hyman SE, Malenka RC, Nestler EJ. Neural mechanisms of addiction: the role of reward-related learning and memory. Annu Rev Neurosci 2006; 29:565-98. [PMID: 16776597 DOI: 10.1146/annurev.neuro.29.051605.113009] [Citation(s) in RCA: 1786] [Impact Index Per Article: 99.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Addiction is a state of compulsive drug use; despite treatment and other attempts to control drug taking, addiction tends to persist. Clinical and laboratory observations have converged on the hypothesis that addiction represents the pathological usurpation of neural processes that normally serve reward-related learning. The major substrates of persistent compulsive drug use are hypothesized to be molecular and cellular mechanisms that underlie long-term associative memories in several forebrain circuits (involving the ventral and dorsal striatum and prefrontal cortex) that receive input from midbrain dopamine neurons. Here we review progress in identifying candidate mechanisms of addiction.
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Affiliation(s)
- Steven E Hyman
- Office of the Provost, Harvard University, Cambridge, Massachusetts 02138, USA.
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532
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Rebec GV, Sun W. Neuronal substrates of relapse to cocaine-seeking behavior: role of prefrontal cortex. J Exp Anal Behav 2006; 84:653-66. [PMID: 16596984 PMCID: PMC1389785 DOI: 10.1901/jeab.2005.105-04] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The return to drug seeking, even after prolonged periods of abstinence, is a defining feature of cocaine addiction. The neural circuitry underlying relapse has been identified in neuropharmacological studies of experimental animals, typically rats, and supported in brain imaging studies of human addicts. Although the nucleus accumbens (NAcc), which has long been implicated in goal-directed behavior, plays a critical role in this circuit, the prefrontal cortex (PFC) appears to process the events that directly trigger relapse: exposure to acute stress, cues previously associated with the drug, and the drug itself. In this paper, we review animal models of relapse and what they have revealed about the mechanisms underlying the involvement of the NAcc and PFC in cocaine-seeking behavior. We also present electrophysiological data from PFC illustrating how the hedonic, motor, motivational, and reinforcing effects of cocaine can be analyzed at the neuronal level. Our preliminary findings suggest a role for PFC in processing information related to cocaine seeking but not the hedonic effects of the drug. Further use of this recording technology can help dissect the functions of PFC and other components of the neural circuitry underlying relapse.
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533
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Kalivas PW, Hu XT. Exciting inhibition in psychostimulant addiction. Trends Neurosci 2006; 29:610-6. [PMID: 16956674 DOI: 10.1016/j.tins.2006.08.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 07/05/2006] [Accepted: 08/25/2006] [Indexed: 10/24/2022]
Abstract
Neuroplasticity induced in the nucleus accumbens by repeated psychostimulant administration is thought to underlie the vulnerability to relapse in addicts. Electrophysiological research presents a contradictory portrait of psychostimulant-induced neuroplasticity, reflecting both increases and decreases in excitatory transmission. Drug-induced adaptations of ionic conductances decrease the intrinsic excitability of individual nucleus accumbens spiny neurons but, in the context of the circuitry in which these neurons are embedded, such reduced intrinsic excitability increases the salience of excitatory drive that is elicited by drug-associated stimuli. Thus, we propose that reduced basal excitability, combined with enhanced excitatory drive by drug-associated stimuli, contributes to the two cardinal features of addiction: reduced responding to natural reward and enduring vulnerability to relapse.
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Affiliation(s)
- Peter W Kalivas
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA.
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534
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Schramm-Sapyta NL, Olsen CM, Winder DG. Cocaine self-administration reduces excitatory responses in the mouse nucleus accumbens shell. Neuropsychopharmacology 2006; 31:1444-51. [PMID: 16205778 DOI: 10.1038/sj.npp.1300918] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Drugs of abuse affect behavior by altering neuronal communication within the brain. Previous research examining the effects of intraperitoneally administered cocaine has revealed that cocaine alters excitatory glutamatergic signaling, both directly through regulation of synaptic function, and indirectly through regulation of cellular excitability in areas of the drug reward circuitry such as the nucleus accumbens (NAcc) and ventral tegmental area. We have now extended these findings by testing the hypothesis that self-administration of cocaine might elicit similar alterations in excitatory signaling in the NAcc shell. We observed that cocaine self-administration reduces synaptically evoked excitatory responses recorded extracellularly in the NAcc shell compared to saline self-administration. This alteration was not accompanied by alterations in paired pulse ratio of synaptically evoked responses or in potentiation of these responses by application of the adenylyl cyclase activator forskolin. This reduction in glutamatergic signaling may be one mechanism by which cocaine exerts its long-term behavioral effects.
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Affiliation(s)
- Nicole L Schramm-Sapyta
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA
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535
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Ball KT, Budreau D, Rebec GV. Context-dependent behavioural and neuronal sensitization in striatum to MDMA (ecstasy) administration in rats. Eur J Neurosci 2006; 24:217-28. [PMID: 16882018 DOI: 10.1111/j.1460-9568.2006.04885.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To investigate the neuronal mechanisms underlying the behavioural alterations that accompany repeated exposure to MDMA (ecstasy), we recorded the activity of > 200 striatal units in response to multiple, intermittent, locomotor-activating doses (5.0 mg/kg) of MDMA. Rats were treated with once-daily injections of either saline or MDMA for 5 days when housed in their home cage, followed by a challenge injection 3-5 days later when housed in a recording chamber. Because contextual drug associations might be particularly important to the expression of behavioural sensitization to chronic MDMA, a separate group of rats received repeated injections of MDMA alternately in the recording chamber or home cage, according to the above timeline. A sensitized locomotor response was observed only in rats that had previously experienced MDMA in the context of the recording chamber, and only on the challenge day. These sensitized animals also showed a decreased basal firing rate in neurons that were subsequently excited by MDMA when compared with the same category of neurons earlier in the treatment regimen. This resulted in a greater percentage increase from the baseline firing rate on the challenge day compared with the first and fifth days of treatment, even though this trend was not evident with an analysis of absolute firing rate. These results strongly support a role for context in the expression of MDMA-induced locomotor sensitization, and implicate striatal involvement in the neurobehavioural changes associated with the repeated use of MDMA.
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Affiliation(s)
- Kevin T Ball
- Department of Psychological and Brain Sciences and Program in Neuroscience, Indiana University, 1101 East 10th Street, Bloomington, IN, USA
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536
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Kruzich PJ, Xi J. Different patterns of pharmacological reinstatement of cocaine-seeking behavior between Fischer 344 and Lewis rats. Psychopharmacology (Berl) 2006; 187:22-9. [PMID: 16418826 DOI: 10.1007/s00213-005-0264-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Accepted: 10/25/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE Fischer 344 (F344) and Lewis (LEW) rats differ in cocaine self-administration behaviors. Whether or not these inbred strains of rats differ in pharmacological reinstatement of cocaine-seeking behavior is unknown. OBJECTIVES The purpose of the present study was to determine if inbred strains of rats demonstrate differences in alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) and cocaine-induced reinstatement of previously extinguished cocaine-seeking behavior. METHODS F344 and LEW rats received indwelling jugular catheters, bilateral guide cannula aimed at the nucleus accumbens core, and were trained to lever press for 0.5 mg/kg intravenous cocaine during 2-h self-administration sessions. Following 14 sessions, rats underwent extinction sessions, where previously reinforced lever pressing resulted in no programmed consequences. Just prior to beginning extinction session 7, rats received an intracranial infusion of saline. Lever pressing was not reinforced. During subsequent extinction sessions, rats received AMPA injections (0.2, 0.4, or 0.6 nM). Dosing order was determined by a within-subject Latin square design. At least two extinction sessions separated each AMPA session. Rats then underwent cocaine-induced reinstatement test sessions (lever pressing was not reinforced). Rats received passive intravenous cocaine (0.0, 0.5, 1.0, or 2.0 mg/kg) after being placed in the experimental chamber. At least two extinction sessions separated each cocaine-prime session, and subjects were tested at each dose according to a within-subjects Latin square design. RESULTS LEW rats demonstrated blunted maximal responding to AMPA-induced reinstatement and heightened sensitivity to cocaine-induced reinstatement compared with F344 rats. CONCLUSIONS This study demonstrates that inbred strains differ in pharmacological reinstatement of cocaine-seeking behavior.
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Affiliation(s)
- Paul J Kruzich
- Department of Physiology, CA 2098, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912, USA.
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537
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Li Z, Gao L, Liu Q, Cao C, Sun XL, Ding JH, Hu G. Aquaporin-4 knockout regulated cocaine-induced behavior and neurochemical changes in mice. Neurosci Lett 2006; 403:294-8. [PMID: 16797122 DOI: 10.1016/j.neulet.2006.05.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 05/02/2006] [Accepted: 05/02/2006] [Indexed: 11/16/2022]
Abstract
Aquaporin-4 (AQP4) is the predominant water channel of brain, which mediates transmembrane water movement at the blood-brain barrier and at the brain-cerebrospinal fluid interface. It has been reported that AQP4 deletion results in an increase of amino acid and monoamine levels in some brain regions of mice, suggesting that AQP4 may participate in region-specific alterations in brain amino acid and monoamine metabolism. In the present study, we examined whether AQP4 affects neurotransmission in acute and chronic cocaine exposure mice. For this purpose, both wild-type and AQP4 knockout mice were used with locomotor activity evaluation and microdialysis methods. The results reveal that AQP4 deletion attenuated locomotor activity in acute and repeated cocaine exposure mice, and induced a decrease of extracellular dopamine and glutamate levels in the nucleus accumbens (NAc), a brain region known to be critically involved in the addictive properties of cocaine. Therefore, AQP4 may play a role in regulating extracellular cocaine-induced dopamine and glutamate release in the brain reward center, and in turn AQP4 deletion may attenuate cocaine reinforcement and dependence.
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Affiliation(s)
- Zhen Li
- Laboratory of Neuropharmacology, Department of Anatomy, Histology & Pharmacology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, Jiangsu 210029, PR China
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538
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Koya E, Spijker S, Voorn P, Binnekade R, Schmidt ED, Schoffelmeer ANM, De Vries TJ, Smit AB. Enhanced cortical and accumbal molecular reactivity associated with conditioned heroin, but not sucrose-seeking behaviour. J Neurochem 2006; 98:905-15. [PMID: 16787418 DOI: 10.1111/j.1471-4159.2006.03917.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Re-exposure to drug-related cues elicits drug-seeking behaviour and relapse in both humans and laboratory animals even after months of abstinence. Identifying neural and molecular substrates underlying conditioned heroin-seeking behaviour will be helpful in understanding mechanisms behind opiate relapse. In humans and animals, brain areas activated by natural reward-related stimuli (e.g. food, sex) do not show a complete overlap with those activated by stimuli associated with drugs of abuse, suggesting the involvement of different circuitry. To that end, we investigated neural reactivity by measuring immediate early gene (IEG) expression patterns in mesocorticolimbic system target areas following cue-induced reinstatement of heroin seeking and compared those IEG expression patterns to what was measured during natural reward (sucrose)-seeking behaviour. Animals were trained to administer heroin associated with a compound audio-visual cue. Re-exposure to the cue after 3 weeks of withdrawal reinstated heroin-seeking behaviour, which resulted in IEG expression of ania-3, MKP-1, c-fos and Nr4a3 in the medial prefrontal cortex (mPFC), and of ania-3 in the orbital frontal cortex (OFC) and nucleus accumbens core (NAC). The expression patterns for heroin-seeking behaviours did not generalize to sucrose-seeking behaviours, indicating that the two behaviours involve different connectivity pathways of neuronal signalling.
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Affiliation(s)
- E Koya
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Free University, Amsterdam, the Netherlands
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539
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Mcgeehan AJ, Olive MF. Attenuation of cocaine-induced reinstatement of cocaine conditioned place preference by acamprosate. Behav Pharmacol 2006; 17:363-7. [PMID: 16914955 DOI: 10.1097/01.fbp.0000224384.01863.5f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Acamprosate (calcium acetylhomotaurinate) is a glutamatergic neuromodulator efficacious at reducing relapse in alcoholic patients. The effect of acamprosate on relapse to other drugs of abuse has received little attention, however, and given increasing evidence that glutamatergic transmission mediates relapse to cocaine-seeking behavior, the purpose of this study was to assess the effects of acamprosate on the reinstatement of a conditioned place preference for cocaine. Mice were conditioned daily with cocaine (15 mg/kg), tested for the establishment of cocaine conditioned place preference, and then retested once weekly to monitor the extinction of the place preference. Following extinction of cocaine conditioned place preference, animals were treated daily with saline or acamprosate (30 or 100 mg/kg) for 3 days, followed by a single injection of cocaine (15 mg/kg) to reinstate conditioned place preference. In mice treated with saline or the low (30 mg/kg) dose of acamprosate, cocaine induced a significant reinstatement of the previously extinguished conditioned place preference; however, this reinstatement was not observed in mice treated with the high (100 mg/kg) dose of acamprosate. These results indicate that acamprosate can attenuate relapse-like behavior in mice and suggest that this compound may be potentially useful in the treatment for cocaine addiction.
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Affiliation(s)
- Andrew J Mcgeehan
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California at San Francisco, Emeryville, California, USA
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540
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Peters J, Kalivas PW. The group II metabotropic glutamate receptor agonist, LY379268, inhibits both cocaine- and food-seeking behavior in rats. Psychopharmacology (Berl) 2006; 186:143-9. [PMID: 16703399 DOI: 10.1007/s00213-006-0372-9] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Accepted: 03/01/2006] [Indexed: 01/08/2023]
Abstract
RATIONALE Group II metabotropic glutamate receptor (mGluR2/3) agonists are proposed to serve as potential treatment for addiction. OBJECTIVES The present study examined the hypothesis that mGluR2/3 agonists exert inhibitory effects on cocaine-induced reinstatement of cocaine-seeking. METHODS Rats were trained to self-administer either cocaine or control reinforcer (food), then responding on the reinforcer-paired lever was extinguished. Reinstatement of responding was induced by a noncontingent presentation of the self-administered reinforcer (10 mg/kg cocaine, i.p. or 765 mg of food). In one experiment, rats were systemically pretreated with vehicle (Veh) or the mGluR2/3 agonist LY379268 (0.3, 1, or 3 mg/kg, i.p.) 30 min before the reinstatement test session. In a second experiment, Veh or LY379268 (0.05, 0.5, or 5 nmol/side) was microinjected into the nucleus accumbens core (NAc core) 5 min before the reinstatement test session. The effects of LY379268 on cocaine- and food-induced reinstatement on reward seeking were assessed. RESULTS Both systemic and intra-NAc core pretreatment with LY379268 inhibited both cocaine- and food-seeking behavior. However, the effect of LY379268 appeared somewhat more effective for cocaine-seeking than food-seeking. CONCLUSIONS These results support a potential therapeutic role for mGluR2/3 agonists on relapse of cocaine-seeking. However, doses that inhibited cocaine-seeking were only threefold lower than those inhibiting food-seeking, indicating possible unacceptable nonspecific effects. In addition, the NAc core is one site of action where the mGluR2/3 agonists elicit effects on reward-seeking behavior.
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Affiliation(s)
- Jamie Peters
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, 29425, USA.
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541
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Schmidt HD, Anderson SM, Famous KR, Kumaresan V, Pierce RC. Anatomy and pharmacology of cocaine priming-induced reinstatement of drug seeking. Eur J Pharmacol 2006; 526:65-76. [PMID: 16321382 DOI: 10.1016/j.ejphar.2005.09.068] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 07/13/2005] [Accepted: 09/23/2005] [Indexed: 12/18/2022]
Abstract
Cocaine addiction in human addicts is characterized by a high rate of relapse following successful detoxification. Relapse to drug taking/seeking can be precipitated by several stimuli including, but not limited to, re-exposure to cocaine itself. In order to understand the mechanisms underlying cocaine craving, a substantial effort has been devoted to elucidating the anatomical and neurochemical bases underlying cocaine priming-induced reinstatement, an animal model of relapse. Here, we review evidence that changes in dopaminergic and glutamatergic transmission in limbic/basal ganglia circuits of interconnected nuclei including the medial prefrontal cortex, nucleus accumbens, ventral pallidum, amygdala, hippocampus, orbitofrontal cortex, neostriatum and thalamus underlie cocaine priming-induced reinstatement of cocaine seeking. Maladaptive changes in the processing of motivationally relevant stimuli by these circuits following cocaine self-administration result in drug craving and compulsive drug seeking upon re-exposure to cocaine.
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Affiliation(s)
- Heath D Schmidt
- Department of Pharmacology, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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542
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Brower V. Loosening addiction's deadly grip. Recent research paints a picture of addiction as a progressive, chronic neurological disease that wreaks havoc with brain chemistry. EMBO Rep 2006; 7:140-2. [PMID: 16452925 PMCID: PMC1369263 DOI: 10.1038/sj.embor.7400635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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543
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Schmidt HD, Anderson SM, Pierce RC. Stimulation of D1-like or D2 dopamine receptors in the shell, but not the core, of the nucleus accumbens reinstates cocaine-seeking behaviour in the rat. Eur J Neurosci 2006; 23:219-28. [PMID: 16420431 DOI: 10.1111/j.1460-9568.2005.04524.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although increases in dopamine transmission in the brain are clearly involved in the reinstatement of cocaine seeking, the role of nucleus accumbens dopamine in cocaine priming-induced reinstatement remains controversial. The goal of these experiments was to evaluate the relative contributions of D1-like and D2-like dopamine receptors in the nucleus accumbens core and shell in the reinstatement of cocaine-seeking behaviour. Initially, rats were trained to press a lever for cocaine (0.25 mg, i.v.) using a fixed-ratio 5 (FR5) schedule of reinforcement. Responding was then extinguished by substituting saline for cocaine. During the reinstatement phase, subtype-specific dopamine receptor agonists were microinjected into the nucleus accumbens core or medial shell in order to assess their ability to induce cocaine seeking. Administration of the D1/D5 dopamine receptor agonist SKF-81297 (1.0 microg) into the nucleus accumbens shell, but not core, reinstated drug-seeking behaviour. Similarly, microinjection of quinpirole (3.0 microg), a D2/D3 dopamine receptor agonist, into the nucleus accumbens shell and not core reinstated drug-seeking behaviour. In contrast, administration of the D3- or D4-preferring dopamine receptor agonists PD 128,907 (1.5 and 3.0 microg) and PD 168,077 (0.3 and 3.0 microg), respectively, did not promote reinstatement when administered into either the core or the shell. Taken together, these results indicate that activation of D1/D5 or D2 dopamine receptors, in the limbic shell subregion of the nucleus accumbens but not the basal ganglia-orientated accumbens core, promotes the reinstatement of cocaine-seeking behaviour.
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Affiliation(s)
- Heath D Schmidt
- Laboratory of Neuropsychopharmacology, Department of Pharmacology, L-603, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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544
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Alleweireldt AT, Hobbs RJ, Taylor AR, Neisewander JL. Effects of SCH-23390 infused into the amygdala or adjacent cortex and basal ganglia on cocaine seeking and self-administration in rats. Neuropsychopharmacology 2006; 31:363-74. [PMID: 15957007 DOI: 10.1038/sj.npp.1300794] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Amygdala D1 receptors have been implicated in the motivating effects of cocaine-conditioned cues and cocaine itself, but the specific nucleus involved is unclear. Thus, we infused the D1 antagonist, SCH-23390, into the rostral basolateral amygdala (rBLA), caudal basolateral amygdala (cBLA), or central amygdala (CEA), and tested its effects on self-administration of cocaine, as well as reinstatement of extinguished cocaine-seeking behavior by cocaine-conditioned cues or cocaine itself. Two anatomical controls, the posterior regions of basal ganglia (BG) and somatosensory/insular cortices (CTX), were also examined. Cocaine self-administration was increased and cue and cocaine reinstatement were decreased by SCH-23390 infusion into every region when examined across the hour test session, with the exception that cBLA infusion did not alter cocaine reinstatement. In the first 20 min of the session, when SCH-23390 was more localized in the target sites, self-administration was increased by infusion into the CEA, cBLA, BG, and CTX, with lesser increases in the rBLA. Cocaine reinstatement was attenuated during the first 20 min only by infusion into the CEA, rBLA, and CTX. Cue reinstatement was not reliably observed in the first 20 min, but there was a trend for attenuation by infusion into the cBLA, and surprisingly, significant attenuations in the BG and CTX. The findings suggest that D1 receptors in subregions of the amygdala play differential roles in the reinforcing/motivational effects of cocaine, while the cue reinstatement effects are less clear. Further research is needed to examine the novel findings that neighboring regions of the BG and CTX may play a role in motivation for cocaine.
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545
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Everitt BJ, Robbins TW. Neural systems of reinforcement for drug addiction: from actions to habits to compulsion. Nat Neurosci 2006; 8:1481-9. [PMID: 16251991 DOI: 10.1038/nn1579] [Citation(s) in RCA: 2543] [Impact Index Per Article: 141.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Drug addiction is increasingly viewed as the endpoint of a series of transitions from initial drug use--when a drug is voluntarily taken because it has reinforcing, often hedonic, effects--through loss of control over this behavior, such that it becomes habitual and ultimately compulsive. Here we discuss evidence that these transitions depend on interactions between pavlovian and instrumental learning processes. We hypothesize that the change from voluntary drug use to more habitual and compulsive drug use represents a transition at the neural level from prefrontal cortical to striatal control over drug seeking and drug taking behavior as well as a progression from ventral to more dorsal domains of the striatum, involving its dopaminergic innervation. These neural transitions may themselves depend on the neuroplasticity in both cortical and striatal structures that is induced by chronic self-administration of drugs.
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Affiliation(s)
- Barry J Everitt
- Department of Experimental Psychology and the MRC-Wellcome Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK.
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546
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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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547
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Hemby SE, Tang W, Muly EC, Kuhar MJ, Howell L, Mash DC. Cocaine-induced alterations in nucleus accumbens ionotropic glutamate receptor subunits in human and non-human primates. J Neurochem 2006; 95:1785-93. [PMID: 16363995 PMCID: PMC3843355 DOI: 10.1111/j.1471-4159.2005.03517.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chronic cocaine and withdrawal induce significant alterations in nucleus accumbens (NAc) glutamatergic function in humans and rodent models of cocaine addiction. Dysregulation of glutamatergic function of the prefrontal cortical-NAc pathway has been proposed as a critical substrate for unmanageable drug seeking. Previously, we demonstrated significant up-regulation of NMDA, (+/-)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate receptor subunit mRNAs and protein levels in the ventral tegmental area (VTA), but not the substantia nigra, of cocaine overdose victims (COD). The present study was undertaken to examine the extent of altered ionotropic glutamate receptor (iGluR) subunit expression in the NAc and the putamen in cocaine overdose victims. Results revealed statistically significant increases in the NAc, but not in the putamen, of NMDA receptor subunit (NR)1 and glutamate receptor subunit (GluR)2/3 wit trends in GluR1 and GluR5 in COD. These results extend our previous finding and indicate pathway-specific alterations in iGluRs in COD. In order to determine that changes were related to cocaine intake and not to other factors in the COD victims, we examined the effects of cocaine intravenous self-administration in rhesus monkeys for 18 months (unit dose of 0.1 mg/kg/injection and daily drug intake of 0.5 mg/kg/session). Total drug intake for the group of four monkeys was 37.9 +/- 4.6 mg/kg. Statistically significant elevations were observed for NR1, GluR1, GluR2/3 and GluR5 (p < 0.05) and a trend towards increased NR1 phosphorylated at serine 896 (p = 0.07) in the NAc but not putamen of monkeys self-administering cocaine compared with controls. These results extend previous results by demonstrating an up-regulation of NR1, GluR2/3 and GluR5 in the NAc and suggest these alterations are pathway specific. Furthermore, these changes may mediate persistent drug intake and craving in the human cocaine abuser.
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Affiliation(s)
- Scott E Hemby
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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548
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Schmidt ED, Voorn P, Binnekade R, Schoffelmeer ANM, De Vries TJ. Differential involvement of the prelimbic cortex and striatum in conditioned heroin and sucrose seeking following long-term extinction. Eur J Neurosci 2006; 22:2347-56. [PMID: 16262673 DOI: 10.1111/j.1460-9568.2005.04435.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Relapse to drug taking is triggered by stimuli previously associated with consumption of drugs of misuse (cues) and involves brain systems controlling motivated behaviour towards natural reinforcers. In this study, we aimed to identify and compare neuronal pathways in corticostriatal systems that control conditioned heroin or natural reward (sucrose) seeking. To that end, rats were trained to self-administer heroin or sucrose in association with an identical compound cue. After more than 3 weeks of abstinence during extinction training, cue exposure robustly reinstated heroin and sucrose seeking, but induced distinct and even opposing changes in the expression of the neuronal activation marker zif268 in the prelimbic cortex and striatal complex, respectively. Because in the prelimbic area zif268 expression was enhanced during cue-induced heroin seeking but unaffected during sucrose seeking, a pharmacological intervention was aimed at this prefrontal region. Injection of a GABA agonist mixture within the prelimbic area enhanced conditioned heroin seeking, but had no effect on conditioned sucrose seeking. Our findings suggest a differential role of the prelimbic area and the striatum in the persistence of heroin vs. sucrose seeking following long-term extinction.
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Affiliation(s)
- E Donné Schmidt
- Research Institute Neurosciences Vrije Universiteit, Center for Neurogenomics and Cognitive Research, Department of Medical Pharmacology, VU medical centre, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
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549
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Czachowski CL. Manipulations of serotonin function in the nucleus accumbens core produce differential effects on ethanol and sucrose seeking and intake. Alcohol Clin Exp Res 2006; 29:1146-55. [PMID: 16046869 DOI: 10.1097/01.alc.0000171944.50381.86] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Behaviorally relevant stimuli, including alcohol, are processed through the nucleus accumbens/ventral tegmental area (VTA)/prefrontal cortex circuit. It is hypothesized that serotonin affects ethanol-directed behaviors by interacting with this system via projections from the dorsal raphe to the nucleus accumbens and VTA. The current studies utilized two different operant paradigms, one focusing on reinforcer seeking and one focusing on reinforcer self-administration (both with an ethanol and a sucrose solution as the reinforcer) to elucidate serotonin-specific regulation of these behaviors. METHODS The present experiments assessed the effects of microinjections of a serotonin1B agonist (CGS12066B) and a serotonin1A agonist (8-OH-DPAT) in the nucleus accumbens core on ethanol- and sucrose-reinforced seeking and intake. In four separate experiments, male Long-Evans rats were trained to complete a single response requirement that resulted in access to 10% ethanol or 2% sucrose for a 20-min drinking period. RESULTS Before microinjections, ethanol-reinforced subjects were consuming an average of 0.5-0.95 g/kg ethanol and making 50-100 responses during intermittent nonreinforced sham (no drug) sessions (sucrose groups had similar baseline response levels). In summary, findings from the four experiments showed the following: (1) manipulations of serotonin function that had effects on ethanol-reinforced responding had either no effect or less pronounced effects on sucrose-reinforced responding; (2) administration of the serotonin1B agonist decreased seeking behaviors to a greater degree than drinking behaviors; and (3) administration of the serotonin1A agonist decreased ethanol intake but not seeking with no impact at all on sucrose-reinforced behaviors. CONCLUSIONS Manipulations of serotonin activity in the nucleus accumbens core had little effect on sucrose-reinforced behaviors and differential effects on ethanol seeking versus intake, suggesting that this area may play a complex but selective role in the stimulus processing of external and internal alcohol-associated cues.
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Affiliation(s)
- Cristine L Czachowski
- Center for Alcohol and Addiction Studies, Department of Psychiatry and Human Behavior, Brown University, Providence, Rhode Island 02912, USA.
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550
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Volkow ND, Li TK. Drugs and alcohol: treating and preventing abuse, addiction and their medical consequences. Pharmacol Ther 2006; 108:3-17. [PMID: 16098597 DOI: 10.1016/j.pharmthera.2005.06.021] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Accepted: 06/06/2005] [Indexed: 01/12/2023]
Abstract
Recent advances in the fields of genetics, molecular biology, behavioral neuropharmacology, and brain imaging have dramatically changed our understanding of the addictive process and why relapse occurs even in the face of catastrophic consequences. Addiction is now recognized as a chronic brain disease that involves complex interactions between repeated exposure to drugs, biological (i.e., genetic and developmental), and environmental (i.e., drug availability, social, and economic variables) factors. Its treatment, therefore, requires, in general, not only a long-term intervention but also a multipronged approach that addresses the psychiatric, medical, legal, and social consequences of addiction. Also, because addiction usually starts in adolescence or early adulthood and is frequently comorbid with mental illness, we need to expand our treatment interventions in this age group both for substance abuse and psychiatric disorders.
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Affiliation(s)
- Nora D Volkow
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA.
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