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Shang Q, Xiao J, Gao B, Liang M, Wang J, Qian H, Xi Z, Li T, Liu X. D1R/PP2A/p-CaMKIIα signaling in the caudate putamen is involved in acute methamphetamine-induced hyperlocomotion. Neurosci Lett 2021; 760:136102. [PMID: 34237414 DOI: 10.1016/j.neulet.2021.136102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/29/2021] [Accepted: 07/02/2021] [Indexed: 10/20/2022]
Abstract
Drug addiction is underscored by the transition from experimental use to dependent use of addictive drugs. Acute use of methamphetamine (METH) causes a range of clinical symptoms, including hyperlocomotion. Dopamine D1 receptor (D1R)-mediated negative regulation of phosphorylated calcium/calmodulin-dependent protein kinase IIα (p-CaMKIIα, threonine [Thr] 286) is involved in the acute effects induced by single METH administration. Protein phosphatase 2A (PP2A) is a potential bridge that links D1R and p-CaMKIIα (Thr 286) after acute METH administration. However, the mechanisms underlying hyperlocomotion induced by single METH administration remain unclear. In this study, SCH23390 (a D1R inhibitor) and LB100 (a PP2A inhibitor) were administered to examine the involvement of D1R and PP2A signaling in acute METH-induced hyperlocomotion in mice. The protein levels of methylated PP2A-C (m-PP2A-C, leucine [Leu] 309), phosphorylated PP2A-C (p-PP2A-C, tyrosine [Tyr] 307), PP2A-C, p-CaMKIIα (Thr 286), and CaMKIIα in the prefrontal cortex (PFc), nucleus accumbens (NAc), and caudate putamen (CPu) were measured. Administration of 0.5 mg/kg SCH23390 reversed the acute METH-induced increase in protein levels of m-PP2A-C (Leu 309) and the decrease in protein levels of p-PP2A-C (Tyr 307) in the CPu, but not in the PFC and NAc. Moreover, prior administration of 0.1 mg/kg LB100 attenuated hyperlocomotion induced by single METH administration and reversed the decrease in protein levels of p-CaMKII (Thr 286) in the PFC, NAc, and CPu. Collectively, these results indicate that the D1R/PP2A/p-CaMKIIα signaling cascade in the CPu may be involved in hyperlocomotion after a single administration of METH.
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Affiliation(s)
- Qing Shang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Jing Xiao
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Baoyao Gao
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Min Liang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Jing Wang
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Hongyan Qian
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Zhijia Xi
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China
| | - Tao Li
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China.
| | - Xinshe Liu
- College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an 710061, Shaanxi, People's Republic of China; Institute of Forensic Injury, Institute of Forensic Bioevidence, Western China Science and Technology Innovation Harbor, Xi'an Jiaotong University, People's Republic of China.
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Dobbs LK, Kaplan AR, Bock R, Phamluong K, Shin JH, Bocarsly ME, Eberhart L, Ron D, Alvarez VA. D1 receptor hypersensitivity in mice with low striatal D2 receptors facilitates select cocaine behaviors. Neuropsychopharmacology 2019; 44:805-816. [PMID: 30504927 PMCID: PMC6372593 DOI: 10.1038/s41386-018-0286-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/16/2018] [Accepted: 11/23/2018] [Indexed: 11/17/2022]
Abstract
Vulnerability for cocaine abuse in humans is associated with low dopamine D2 receptor (D2R) availability in the striatum. The mechanisms driving this vulnerability are poorly understood. In this study, we found that downregulating D2R expression selectively in striatal indirect-pathway neurons triggers a multitude of changes in D1 receptor (D1R)-expressing direct-pathway neurons, which comprise the other main subpopulation of striatal projection neurons. These changes include a leftward shift in the dose-response to a D1-like agonist that indicates a behavioral D1R hypersensitivity, a shift from PKA to ERK intracellular signaling cascades upon D1R activation, and a reduction in the density of bridging collaterals from D1R-expressing neurons to pallidal areas. We hypothesize that the D1R hypersensitivity underlies abuse vulnerability by facilitating the behavioral responses to repeated cocaine, such as locomotor sensitization and drug self-administration. We found evidence that littermate control mice develop D1R hypersensitivity after they are sensitized to cocaine. Indeed, D1-like agonist and cocaine cross-sensitize in control littermates and this effect was potentiated in mice lacking striatal D2Rs from indirect-pathway neurons. To our surprise, mice with low striatal D2Rs acquired cocaine self-administration similarly to littermate controls and showed no significant change in motivation to take cocaine but lower seeking. These findings indicate that downregulation of striatal D2Rs triggers D1R hypersensitivity to facilitate cocaine locomotor sensitization, which by itself was not associated with greater cocaine taking or seeking under the conditions tested.
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Affiliation(s)
- Lauren K Dobbs
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
- Center on Compulsive Behaviors, Intramural Research Program, NIH, Bethesda, MD, USA
| | - Alanna R Kaplan
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
| | - Roland Bock
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
- Center on Compulsive Behaviors, Intramural Research Program, NIH, Bethesda, MD, USA
| | - Khanhky Phamluong
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - J Hoon Shin
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
| | - Miriam E Bocarsly
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
- Postdoctoral Research Associate Program, National Institute of General Medical Sciences, NIH, Bethesda, MD, USA
| | - Lindsay Eberhart
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA
| | - Dorit Ron
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Veronica A Alvarez
- Laboratory on the Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, Intramural Research Program, NIH, Bethesda, MD, USA.
- Center on Compulsive Behaviors, Intramural Research Program, NIH, Bethesda, MD, USA.
- National Institute on Drug Abuse, Intramural Research Program, NIH, Baltimore, MD, USA.
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García-Pardo MP, Roger-Sanchez C, Rodríguez-Arias M, Miñarro J, Aguilar MA. Pharmacological modulation of protein kinases as a new approach to treat addiction to cocaine and opiates. Eur J Pharmacol 2016; 781:10-24. [DOI: 10.1016/j.ejphar.2016.03.065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/28/2016] [Accepted: 03/31/2016] [Indexed: 12/13/2022]
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White SL, Ortinski PI, Friedman SH, Zhang L, Neve RL, Kalb RG, Schmidt HD, Pierce RC. A Critical Role for the GluA1 Accessory Protein, SAP97, in Cocaine Seeking. Neuropsychopharmacology 2016; 41:736-50. [PMID: 26149358 PMCID: PMC4707820 DOI: 10.1038/npp.2015.199] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 06/05/2015] [Accepted: 06/06/2015] [Indexed: 01/05/2023]
Abstract
A growing body of evidence indicates that the transport of GluA1 subunit-containing calcium-permeable AMPA receptors (CP-AMPARs) to synapses in subregions of the nucleus accumbens promotes cocaine seeking. Consistent with these findings, the present results show that administration of the CP-AMPAR antagonist, Naspm, into the caudal lateral core or caudal medial shell of the nucleus accumbens attenuated cocaine priming-induced reinstatement of drug seeking. Moreover, viral-mediated overexpression of 'pore dead' GluA1 subunits (via herpes simplex virus (HSV) GluA1-Q582E) in the lateral core or medial shell attenuated the reinstatement of cocaine seeking. The overexpression of wild-type GluA1 subunits (via HSV GluA1-WT) in the medial shell, but not the lateral core, enhanced the reinstatement of cocaine seeking. These results indicate that activation of GluA1-containing AMPARs in subregions of the nucleus accumbens reinstates cocaine seeking. SAP97 and 4.1N are proteins involved in GluA1 trafficking to and stabilization in synapses; SAP97-GluA1 interactions also influence dendritic growth. We next examined potential roles of SAP97 and 4.1N in cocaine seeking. Viral-mediated expression of a microRNA that reduces SAP97 protein expression (HSV miSAP97) in the medial accumbens shell attenuated cocaine seeking. In contrast, a virus that overexpressed a dominant-negative form of a 4.1N C-terminal domain (HSV 4.1N-CTD), which prevents endogenous 4.1N binding to GluA1 subunits, had no effect on cocaine seeking. These results indicate that the GluA1 subunit accessory protein SAP97 may represent a novel target for pharmacotherapeutic intervention in the treatment of cocaine craving.
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Affiliation(s)
- Samantha L White
- Department of Psychiatry, Center for Neurobiology and Behavior, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Pavel I Ortinski
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Shayna H Friedman
- Department of Psychiatry, Center for Neurobiology and Behavior, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Lei Zhang
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Abramson Research Center 814, Philadelphia, PA, USA
| | - Rachael L Neve
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research at the Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Robert G Kalb
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Abramson Research Center 814, Philadelphia, PA, USA
| | - Heath D Schmidt
- Department of Psychiatry, Center for Neurobiology and Behavior, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - R Christopher Pierce
- Department of Psychiatry, Center for Neurobiology and Behavior, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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CaM Kinases: From Memories to Addiction. Trends Pharmacol Sci 2015; 37:153-166. [PMID: 26674562 DOI: 10.1016/j.tips.2015.11.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 10/30/2015] [Accepted: 11/02/2015] [Indexed: 12/29/2022]
Abstract
Drug addiction is a major psychiatric disorder with a neurobiological basis that is still insufficiently understood. Initially, non-addicted, controlled drug consumption and drug instrumentalization are established. They comprise highly systematic behaviours acquired by learning and the establishment of drug memories. Ca(2+)/calmodulin-dependent protein kinases (CaMKs) are important Ca(2+) sensors translating glutamatergic activation into synaptic plasticity during learning and memory formation. Here we review the role of CaMKs in the establishment of drug-related behaviours in animal models and in humans. Converging evidence now shows that CaMKs are a crucial mechanism of how addictive drugs induce synaptic plasticity and establish various types of drug memories. Thereby, CaMKs are not only molecular relays for glutamatergic activity but they also directly control dopaminergic and serotonergic activity in the mesolimbic reward system. They can now be considered as major molecular pathways translating normal memory formation into establishment of drug memories and possibly transition to drug addiction.
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Zhou L, Sun WL, Young AB, Lee K, McGinty JF, See RE. Oxytocin reduces cocaine seeking and reverses chronic cocaine-induced changes in glutamate receptor function. Int J Neuropsychopharmacol 2014; 18:pyu009. [PMID: 25539504 PMCID: PMC4368863 DOI: 10.1093/ijnp/pyu009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Oxytocin, a neurohypophyseal neuropeptide, is a potential mediator and regulator of drug addiction. However, the cellular mechanisms of oxytocin in drug seeking remain unknown. METHODS In the present study, we used a self-administration/reinstatement model to study the effects of oxytocin on cocaine seeking and its potential interaction with glutamate function at the receptor level. RESULTS Systemic oxytocin dose-dependently reduced cocaine self-administration during various schedules of reinforcement, including fixed ratio 1, fixed ratio 5, and progressive ratio. Oxytocin also attenuated reinstatement to cocaine seeking induced by cocaine prime or conditioned cues. Western-blot analysis indicated that oxytocin increased phosphorylation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptor GluA1 subunit at the Ser 845 site with or without accompanying increases in phosphorylation of extracellular signal-regulated kinase, in several brain regions, including the prefrontal cortex, bed nucleus of the stria terminalis, amygdala, and dorsal hippocampus. Immunoprecipitation of oxytocin receptor and GluA1 subunit receptors further demonstrated a physical interaction between these 2 receptors, although the interaction was not influenced by chronic cocaine or oxytocin treatment. Oxytocin also attenuated sucrose seeking in a GluA1- or extracellular-signal-regulated kinase-independent manner. CONCLUSIONS These findings suggest that oxytocin mediates cocaine seeking through interacting with glutamate receptor systems via second messenger cascades in mesocorticolimbic regions.
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Affiliation(s)
- Luyi Zhou
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See)
| | - Wei-Lun Sun
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See)
| | - Amy B Young
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See)
| | - Kunhee Lee
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See)
| | - Jacqueline F McGinty
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See)
| | - Ronald E See
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina (Drs Zhou, Sun, Young, Lee, McGinty, and See).
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Easton AC, Lourdusamy A, Havranek M, Mizuno K, Solati J, Golub Y, Clarke TK, Vallada H, Laranjeira R, Desrivières S, Moll GH, Mössner R, Kornhuber J, Schumann G, Giese KP, Fernandes C, Quednow BB, Müller CP. αCaMKII controls the establishment of cocaine's reinforcing effects in mice and humans. Transl Psychiatry 2014; 4:e457. [PMID: 25290264 PMCID: PMC4350526 DOI: 10.1038/tp.2014.97] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/18/2014] [Accepted: 08/21/2014] [Indexed: 12/23/2022] Open
Abstract
Although addiction develops in a considerable number of regular cocaine users, molecular risk factors for cocaine dependence are still unknown. It was proposed that establishing drug use and memory formation might share molecular and anatomical pathways. Alpha-Ca(2+)/calmodulin-dependent protein kinase-II (αCaMKII) is a key mediator of learning and memory also involved in drug-related plasticity. The autophosphorylation of αCaMKII was shown to accelerate learning. Thus, we investigated the role of αCaMKII autophosphorylation in the time course of establishing cocaine use-related behavior in mice. We found that αCaMKII autophosphorylation-deficient αCaMKII(T286A) mice show delayed establishment of conditioned place preference, but no changes in acute behavioral activation, sensitization or conditioned hyperlocomotion to cocaine (20 mg kg(-1), intraperitoneal). In vivo microdialysis revealed that αCaMKII(T286A) mice have blunted dopamine (DA) and blocked serotonin (5-HT) responses in the nucleus accumbens (NAcc) and prefrontal cortex after acute cocaine administration (20 mg kg(-1), intraperitoneal), whereas noradrenaline responses were preserved. Under cocaine, the attenuated DA and 5-HT activation in αCaMKII(T286A) mice was followed by impaired c-Fos activation in the NAcc. To translate the rodent findings to human conditions, several CAMK2A gene polymorphisms were tested regarding their risk for a fast establishment of cocaine dependence in two independent samples of regular cocaine users from Brazil (n=688) and Switzerland (n=141). A meta-analysis across both samples confirmed that CAMK2A rs3776823 TT-allele carriers display a faster transition to severe cocaine use than C-allele carriers. Together, these data suggest that αCaMKII controls the speed for the establishment of cocaine's reinforcing effects.
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Affiliation(s)
- A C Easton
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
| | - A Lourdusamy
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
- Faculty of Medicine and Health Sciences, School of Medicine, University of Nottingham, Nottingham, UK
| | - M Havranek
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - K Mizuno
- Centre for the Cellular Basis of Behavior, Institute of Psychiatry, King's College London, London, UK
| | - J Solati
- Department of Child and Adolescent Mental Health, University Clinic Erlangen, Erlangen, Germany
- Department of Biology, Faculty of Science, Karaj Branch, Islamic Azad University, Karaj, Iran
| | - Y Golub
- Department of Child and Adolescent Mental Health, University Clinic Erlangen, Erlangen, Germany
| | - T-K Clarke
- Translational Research Laboratory, Department of Psychiatry, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - H Vallada
- Department and Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
| | - R Laranjeira
- UNIAD, Federal University of São Paulo, São Paulo, Brazil
| | - S Desrivières
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
| | - G H Moll
- Department of Child and Adolescent Mental Health, University Clinic Erlangen, Erlangen, Germany
| | - R Mössner
- Department of Psychiatry, University of Bonn, Bonn, Germany
| | - J Kornhuber
- Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - G Schumann
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
| | - K P Giese
- Centre for the Cellular Basis of Behavior, Institute of Psychiatry, King's College London, London, UK
| | - C Fernandes
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
| | - B B Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - C P Müller
- MRC Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK
- Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
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Short-term abstinence from cocaine self-administration, but not passive cocaine infusion, elevates αCaMKII autophosphorylation in the rat nucleus accumbens and medial prefrontal cortex. Int J Neuropsychopharmacol 2014; 17:323-9. [PMID: 23953174 DOI: 10.1017/s1461145713000916] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increases in alpha calcium/calmodulin-dependent protein kinase type II (αCaMKII) activity in the nucleus accumbens shell has been proposed as a core component in the motivation to self-administer cocaine and in priming-induced drug-seeking. Since cocaine withdrawal promotes drug-seeking, we hypothesized that abstinence from cocaine self-administration should enhance αCaMKII as well. We found that short-term abstinence from contingent, but not non-contingent, cocaine i.v. self-administration (2 h/d for 14 d; 0.25 mg/0.1 ml, 6 s infusion) elevates αCaMKII autophosphorylation, but not the kinase expression, in a dynamic, time- and brain region-dependent manner. Increased αCaMKII autophosphorylation in the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC), but not dorsolateral striatum (dlS), was found 24 h, but not immediately, after the last cocaine self-administration session. Notably, in the mPFC, but not NAc and dlS, αCaMKII autophosphorylation was still enhanced 7 d later. The persistent enhancement in the mPFC of abstinent rats may represent a previously unappreciated contribution to initial incubation of cocaine-seeking.
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