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Amaral IM, Scheffauer L, Hofer A, El Rawas R. Protein kinases in natural versus drug reward. Pharmacol Biochem Behav 2022; 221:173472. [PMID: 36244528 DOI: 10.1016/j.pbb.2022.173472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/27/2022] [Accepted: 10/05/2022] [Indexed: 12/14/2022]
Abstract
Natural and drug rewards act on the same neural pathway, the mesolimbic dopaminergic system. In brain regions such as the nucleus accumbens and ventral tegmental area, drugs of abuse-induced stimulation of signaling pathways can lead to synaptic reshaping within this system. This is believed to be underlying the maladaptive alterations in behaviors associated with addiction. In this review, we discuss animal studies disclosing the implication of several protein kinases, namely protein kinase A (PKA), extracellular signal regulated kinase (ERK) mitogen-activated protein kinases (MAPK), p38 MAPK, and calcium/calmodulin-dependent kinase II (CaMKII), in reward-related brain regions in drug and natural reward. Furthermore, we refer to studies that helped pave the way toward a better understanding of the neurobiology underlying non-drug and drug reward through genetic deletion or brain region-specific pharmacological inhibition of these kinases. Whereas the role of kinases in drug reward has been extensively studied, their implication in natural reward, such as positive social interaction, is less investigated. Discovering molecular candidates, recruited specifically by drug versus natural rewards, can promote the identification of novel targets for the pharmacological treatment of addiction with less off-target effects and being effective when used combined with behavioral-based therapies.
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Affiliation(s)
- Inês M Amaral
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, Austria.
| | - Laura Scheffauer
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, Austria.
| | - Alex Hofer
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, Austria.
| | - Rana El Rawas
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, Austria.
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2
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Amaral IM, Hofer A, El Rawas R. Implication of Extracellular Signal-Regulated Kinase in the Expression of Natural Reward: Evidence Not Found. Front Behav Neurosci 2022; 16:856675. [PMID: 35368299 PMCID: PMC8973696 DOI: 10.3389/fnbeh.2022.856675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Many studies have implicated extracellular signal-regulated kinase (ERK) in drug-rewarding properties. Yet, only few investigated whether ERK also mediates the naturally rewarding stimuli. In this study, we compared ERK activation in the nucleus accumbens (NAc) after cocaine reward and after positive social interaction (SI) with a partner-reward in male rats. With our protocol, ERK phosphorylation in the NAc was not increased after cocaine reward. In addition, the interaction with a social partner did not alter ERK activation in the NAc. These results suggest that ERK in the NAc may not be involved in natural reward learning. SI in an alternative context to the one associated with drugs of abuse can abolish drug preference. Given that intra-NAc core ERK inhibition impaired the expression of cocaine preference, we wanted to investigate whether the protective effects of SI when an individual is allowed to interact with a social partner in an alternative context to the one associated with drugs during the learning phase are enhanced by ERK inhibition. For that, U0126 was bilaterally infused into the NAc core of rats conditioned with cocaine in one context and with SI in the opposite context before assessing the expression of reward-related learning. Intra-NAc core ERK inhibition was ineffective to impair the expression of drug reward as previously demonstrated, when a social partner was available in an alternative context. Thus, the effects of the pharmacological manipulations based on decreasing ERK activity are not cumulative to other treatments for drug addiction based on SI.
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Context evoked morphine conditioned effects can be equivalent to morphine induced drug effects in terms of behavioral response and ERK activation in reward associated subcortical brain structures. Pharmacol Biochem Behav 2022; 214:173356. [PMID: 35181379 DOI: 10.1016/j.pbb.2022.173356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 12/29/2022]
Abstract
Conditioned drug cues can evoke brief drug-like responses. In this report we show that using brief test sessions, contextual cues can induce conditioned hyperlocomotion and ERK responses equivalent to morphine induced responses. To assess acute unconditioned effects, rats that received morphine (MOR-1) or vehicle (VEH-1), were immediately placed onto an arena for a 5-min locomotion recording session after which ERK was measured in the ventral tegmental area (VTA) and nucleus accumbens (NAc). There were no differences in locomotion between the groups. However, the MOR-1 group had strong ERK activation in VTA and NAc. To assess MOR-conditioned effects, a chronic phase was carried out according to a Pavlovian conditioning protocol. There were two MOR paired groups (MORP), one MOR unpaired (MOR-UP) group and two VEH groups. The treatments were administered over 5 daily five minute test sessions. The final conditioning test was on day 6, in which one of the MOR-P groups and one of the VEH groups received VEH (MOR-P/VEH-6 and VEH/VEH-6, respectively). The other MOR-P group and VEH group received MOR (MOR-P/MOR; VEH/MOR-6, respectively). The MOR-UP group received VEH (MOR-UP/VEH-6). Rats received the treatments immediately prior to a 5-min arena test, and after the session ERK was measured. No morphine induced locomotor stimulation was observed on day 1 but on days 2 to 5, hyperlocomotion in both MOR-P groups occurred. On test day 6, the MOR-P/VEH-6 and the MOR-P/MOR-6 groups had comparable locomotor stimulant responses and similar ERK activity in the VTA and NAc. The MOR-UP group did not differ from the VEH group. We suggest that ERK activation evoked by acute morphine served as a Pavlovian unconditioned stimulus to enable the contextual cues to acquire morphine conditioned stimulus properties and increase the incentive value of the contextual cues.
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Piva A, Caffino L, Padovani L, Pintori N, Mottarlini F, Sferrazza G, Paolone G, Fumagalli F, Chiamulera C. The metaplastic effects of ketamine on sucrose renewal and contextual memory reconsolidation in rats. Behav Brain Res 2020; 379:112347. [DOI: 10.1016/j.bbr.2019.112347] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/15/2022]
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Mauna JC, Harris SS, Pino JA, Edwards CM, DeChellis-Marks MR, Bassi CD, Garcia-Olivares J, Amara SG, Guajardo FG, Sotomayor-Zarate R, Terminel M, Castañeda E, Vergara M, Baust T, Thiels E, Torres GE. G protein βγ subunits play a critical role in the actions of amphetamine. Transl Psychiatry 2019; 9:81. [PMID: 30745563 PMCID: PMC6370791 DOI: 10.1038/s41398-019-0387-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/30/2018] [Accepted: 01/01/2019] [Indexed: 11/18/2022] Open
Abstract
Abnormal levels of dopamine (DA) are thought to contribute to several neurological and psychiatric disorders including drug addiction. Extracellular DA levels are regulated primarily via reuptake by the DA transporter (DAT). Amphetamine, a potent psychostimulant, increases extracellular DA by inducing efflux through DAT. Recently, we discovered that G protein βγ subunits (Gβγ) interact with DAT, and that in vitro activation of Gβγ promotes DAT-mediated efflux. Here, we investigated the role of Gβγ in the actions of amphetamine in DA neurons in culture, ex vivo nucleus accumbens (NAc), and freely moving rats. Activation of Gβγ with the peptide myr-Ser-Ile-Arg-Lys-Ala-Leu-Asn-Ile-Leu-Gly-Tyr-Pro-Asp-Tyr-Asp (mSIRK) in the NAc potentiated amphetamine-induced hyperlocomotion, but not cocaine-induced hyperlocomotion, and systemic or intra-accumbal administration of the Gβγ inhibitor gallein attenuated amphetamine-induced, but not cocaine-induced hyperlocomotion. Infusion into the NAc of a TAT-fused peptide that targets the Gβγ-binding site on DAT (TAT-DATct1) also attenuated amphetamine-induced but not cocaine-induced hyperlocomotion. In DA neurons in culture, inhibition of Gβγ with gallein or blockade of the Gβγ-DAT interaction with the TAT-DATct1 peptide decreased amphetamine-induced DA efflux. Furthermore, activation of Gβγ with mSIRK potentiated and inhibition of Gβγ with gallein reduced amphetamine-induced increases of extracellular DA in the NAc in vitro and in freely moving rats. Finally, systemic or intra-accumbal inhibition of Gβγ with gallein blocked the development of amphetamine-induced, but not cocaine-induced place preference. Collectively, these results suggest that interaction between Gβγ and DAT plays a critical role in the actions of amphetamine and presents a novel target for modulating the actions of amphetamine in vivo.
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Affiliation(s)
- J. C. Mauna
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - S. S. Harris
- 0000 0004 1936 8091grid.15276.37Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL USA
| | - J. A. Pino
- 0000 0004 1936 8091grid.15276.37Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL USA
| | - C. M. Edwards
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - M. R. DeChellis-Marks
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - C. D. Bassi
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - J. Garcia-Olivares
- 0000 0001 2297 5165grid.94365.3dLaboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, NIH, Bethesda, MD USA
| | - S. G. Amara
- 0000 0001 2297 5165grid.94365.3dLaboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, NIH, Bethesda, MD USA
| | - F. G. Guajardo
- 0000 0004 1936 8091grid.15276.37Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL USA ,0000 0000 8912 4050grid.412185.bLaboratory of Neurochemistry and Neuropharmacology, Center for Neurobiology and Brain Plasticity, Universidad de Valparaíso, Valparaíso, Chile
| | - R. Sotomayor-Zarate
- 0000 0000 8912 4050grid.412185.bLaboratory of Neurochemistry and Neuropharmacology, Center for Neurobiology and Brain Plasticity, Universidad de Valparaíso, Valparaíso, Chile
| | - M. Terminel
- 0000 0001 0668 0420grid.267324.6Department of Psychology, University of Texas at El Paso, El Paso, TX USA
| | - E. Castañeda
- 0000 0001 0668 0420grid.267324.6Department of Psychology, University of Texas at El Paso, El Paso, TX USA
| | - M. Vergara
- 0000 0004 1936 8091grid.15276.37Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL USA
| | - T. Baust
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - E. Thiels
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA USA
| | - G. E. Torres
- 0000 0004 1936 8091grid.15276.37Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL USA ,0000 0004 1936 8091grid.15276.37Center for Addiction Research and Education, University of Florida College of Medicine, Gainesville, FL USA
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Cell type-specific activation of mitogen-activated protein kinase in D1 receptor-expressing neurons of the nucleus accumbens potentiates stimulus-reward learning in mice. Sci Rep 2018; 8:14413. [PMID: 30258218 PMCID: PMC6158283 DOI: 10.1038/s41598-018-32840-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 09/12/2018] [Indexed: 01/11/2023] Open
Abstract
Medium spiny neurons (MSN) in the nucleus accumbens (NAc) are a fundamental component of various aspects of motivated behavior. Although mitogen-activated protein kinase (MAPK) signaling plays a crucial role in several types of learning, the cell type-specific role of MAPK pathway in stimulus-reward learning and motivation remains unclear. We herein investigated the role of MAPK in accumbal MSNs in reward-associated learning and memory. During the acquisition of Pavlovian conditioning, the number of phosphorylated MAPK1/3-positive cells was increased significantly and exclusively in the NAc core by 7-days of extensive training. MAPK signaling in the respective D1R- and D2R-MSNs was manipulated by transfecting an adeno-associated virus (AAV) plasmid into the NAc of Drd1a-Cre and Drd2-Cre transgenic mice. Potentiation of MAPK signaling shifted the learning curve of Pavlovian conditioning to the left only in Drd1a-Cre mice, whereas such manipulation in D2R-MSNs had negligible effects. In contrast, MAPK manipulation in D2R-MSNs of the NAc core significantly increased motivation for food rewards as found in Drd1a-Cre mice. These results suggest that MAPK signaling in the D1R-MSNs of NAc core plays an important role in stimulus-reward learning, while MAPK signaling in both D1R- and D2R-MSNs is involved in motivation for natural rewards.
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Guo N, Zhang X, Huang M, Li X, Li Y, Zhou X, Bai J. Geranylgeranylacetone blocks the reinstatement of morphine-conditioned place preference. Neuropharmacology 2018; 143:63-70. [PMID: 30240785 DOI: 10.1016/j.neuropharm.2018.09.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 08/24/2018] [Accepted: 09/17/2018] [Indexed: 12/16/2022]
Abstract
Morphine is widely used for clinical pain management and induces the dependence. Addiction to morphine is a major public health issue. Geranylgeranylacetone (GGA) is widely used in clinic for treating ulcer. GGA induces expression of thioredoxin-1 (Trx-1) extensively. Trx-1 is a redox regulating protein and plays protecting roles in nervous system. GGA prevents mice against morphine-induced hyperlocomotion, rewarding effect, and withdrawal syndrome. However, whether GGA blocks morphine-conditioned place preference (CPP) reinstatement is still unknown. In the present study, we found that GGA administration blocked the reinstatement of morphine-CPP. The expressions of Trx-1, N-methyl d-aspartate receptor 2B subunit (NR2B), phosphorylated Ca2+/calmodulin-dependent protein kinase II (p-CaMKII), phosphorylated extracellular signaling regulated kinases (p-ERK), and phosphorylated cAMP-response element binding protein (p-CREB) were induced in nucleus accumbens (NAc) and hippocampus by morphine or GGA, whereas these proteins were not changed by morphine in GGA-treated mice. Our results indicate that GGA may prevent the reinstatement of morphine-CPP through strengthening the expression of Trx-1 and regulating NR2B/ERK pathway. Thus, we suggest that GGA may be a promising therapeutic candidate for morphine-induced relapse.
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Affiliation(s)
- Ningning Guo
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Xianwen Zhang
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Mengbing Huang
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Xiang Li
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China; Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Ye Li
- Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Xiaoshuang Zhou
- Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China
| | - Jie Bai
- Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China.
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Sucharski F, Noga MJ, Suder P, Kotlińska J, Silberring J. Integrated workflow for quantitative phosphoproteomic analysis of the selected brain structures in development of morphine dependence. Pharmacol Rep 2014; 66:1003-10. [DOI: 10.1016/j.pharep.2014.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/20/2014] [Accepted: 06/05/2014] [Indexed: 11/25/2022]
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9
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Kirschmann EKZ, Mauna JC, Willis CM, Foster RL, Chipman AM, Thiels E. Appetitive cue-evoked ERK signaling in the nucleus accumbens requires NMDA and D1 dopamine receptor activation and regulates CREB phosphorylation. ACTA ACUST UNITED AC 2014; 21:606-15. [PMID: 25322796 PMCID: PMC4201811 DOI: 10.1101/lm.035113.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Conditioned stimuli (CS) can modulate reward-seeking behavior. This modulatory effect can be maladaptive and has been implicated in excessive reward seeking and relapse to drug addiction. We previously demonstrated that exposure to an appetitive CS causes an increase in the activation of extracellular signal-regulated kinase (ERK) and cyclic-AMP response-element binding protein (CREB) in the nucleus accumbens (NAc) of rats, and that CS-evoked ERK activation is critical for CS control over reward seeking. To elucidate the mechanism that mediates CS-driven ERK activation in the NAc, we selectively blocked NMDA glutamate or D1 dopamine receptors in the NAc. To determine whether CS-driven ERK and CREB activation are linked, we selectively blocked ERK signaling in the NAc. We found that both NMDA and D1 receptors are critical for CS-driven ERK signaling in the NAc, and that this recruitment of the ERK cascade is responsible for increased CREB activation in the presence of the CS. Our findings suggest that activation of the NMDAR-D1R/ERK/CREB signal transduction pathway plays a critical role in the control of reward-seeking behavior by reward-predictive cues.
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Affiliation(s)
- Erin K Z Kirschmann
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Jocelyn C Mauna
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Cory M Willis
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Rebecca L Foster
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Amanda M Chipman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Edda Thiels
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Cerovic M, d'Isa R, Tonini R, Brambilla R. Molecular and cellular mechanisms of dopamine-mediated behavioral plasticity in the striatum. Neurobiol Learn Mem 2013; 105:63-80. [PMID: 23827407 DOI: 10.1016/j.nlm.2013.06.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/20/2013] [Accepted: 06/23/2013] [Indexed: 12/25/2022]
Abstract
The striatum is the input structure of the basal ganglia system. By integrating glutamatergic signals from cortical and subcortical regions and dopaminergic signals from mesolimbic nuclei the striatum functions as an important neural substrate for procedural and motor learning as well as for reward-guided behaviors. In addition, striatal activity is significantly altered in pathological conditions in which either a loss of dopamine innervation (Parkinson's disease) or aberrant dopamine-mediated signaling (drug addiction and L-DOPA induced dyskinesia) occurs. Here we discuss cellular mechanisms of striatal synaptic plasticity and aspects of cell signaling underlying striatum-dependent behavior, with a major focus on the neuromodulatory action of the endocannabinoid system and on the role of the Ras-ERK cascade.
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Affiliation(s)
- Milica Cerovic
- School of Biosciences, Cardiff University, CF10 3AX Cardiff, UK
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11
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Remus ML, Thiels E. Stimulus-specific and differential distribution of activated extracellular signal-regulated kinase in the nucleus accumbens core and shell during Pavlovian-instrumental transfer. Brain Struct Funct 2013; 218:913-27. [PMID: 22763576 PMCID: PMC3676472 DOI: 10.1007/s00429-012-0438-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 06/09/2012] [Indexed: 11/28/2022]
Abstract
The ability of reward-predictive cues to potentiate reward-seeking behavior--a phenomenon termed Pavlovian--instrumental transfer (PIT)--depends on the activation of extracellular signal-regulated kinase (ERK) in the nucleus accumbens (NAc). Here, we utilized immunohistochemistry to investigate the subregional pattern of ERK activation during PIT, and the contribution of different elements in the PIT condition to the distribution of ERK signaling in the NAc of rats. We found that the occurrence of reward-seeking behavior (lever pressing) did not affect ERK activation in either the core or the shell of the NAc. In contrast, presentation of the reward-predictive cue (auditory conditioned stimulus) caused a significant increase in ERK activation in both subregions of the NAc, with the effect being slightly more robust in the core than the shell. Different from the pattern evoked by the reward-predictive cue, presentation of the reward itself (food pellets) had no effect on ERK activation in the core but caused a pronounced increase in ERK activation in the shell. Taken together, our results demonstrate that ERK signaling in the NAc during PIT involves both the core and the shell and is driven by the conditioned cue irrespective of whether the situation permits engagement in reward-seeking behavior. Furthermore, our results show that the subregional distribution of ERK signaling in the NAc evoked by rewards differs from that evoked by cues that predict them. The stimulus-specific differential pattern of ERK signaling described here may present the molecular complement to stimulus-specific increases in NAc cell firing reported previously.
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Affiliation(s)
- Merissa L Remus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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Extracellular signal-regulated kinase in the basolateral amygdala, but not the nucleus accumbens core, is critical for context-response-cocaine memory reconsolidation in rats. Neuropsychopharmacology 2013; 38:753-62. [PMID: 23232446 PMCID: PMC3671999 DOI: 10.1038/npp.2012.238] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The reconsolidation of cocaine memories following retrieval is necessary for the sustained ability of a cocaine-paired environmental context to elicit cocaine seeking. Extracellular signal-regulated kinase (ERK) is an intracellular signaling molecule involved in nucleus accumbens core (NACc)-mediated reconsolidation of Pavlovian cocaine memories. Here, we used a rodent model of drug context-elicited relapse to test the hypothesis that ERK would be similarly required for the reconsolidation of context-response-cocaine memories that underlie drug context-induced reinstatement of instrumental cocaine-seeking behavior, with a focus on the NACc and on the basolateral amygdala (BLA), another important locus for the reconsolidation of cocaine memories. We show that the mitogen-activated protein kinase (MEK)/ERK1/2 inhibitor, U0126 (1.0 μg/0.5 μl/hemisphere), microinfused bilaterally into the BLA--but not the NACc--immediately after brief re-exposure to a previously cocaine-paired context (that is, cocaine-memory reactivation), significantly attenuated subsequent drug context-induced cocaine seeking relative to vehicle (VEH). This effect in the BLA was associated with a transient inhibition of ERK1/2 phosphorylation, and it depended on memory reactivation given that U0126 administered following exposure to a novel context did not alter subsequent cocaine seeking. Furthermore, similar to U0126, baclofen+muscimol-induced (B+M; 106.8/5.7 ng/0.5 μl/hemisphere) neural inactivation of the NACc, following cocaine-memory reactivation, failed to alter subsequent cocaine seeking. These findings demonstrate that ERK activation in the BLA, but not the NACc, is required for the reconsolidation of context-response-cocaine associative memories. Together with prior research, these results suggest that contextual drug-memory reconsolidation in Pavlovian and instrumental settings involves distinct neuroanatomical mechanisms.
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Nasser HM, McNally GP. Neural correlates of appetitive-aversive interactions in Pavlovian fear conditioning. Learn Mem 2013; 20:220-8. [DOI: 10.1101/lm.029744.112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Guegan T, Cutando L, Gangarossa G, Santini E, Fisone G, Martinez A, Valjent E, Maldonado R, Martin M. Operant behavior to obtain palatable food modifies ERK activity in the brain reward circuit. Eur Neuropsychopharmacol 2013; 23:240-52. [PMID: 22580057 DOI: 10.1016/j.euroneuro.2012.04.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/28/2012] [Accepted: 04/14/2012] [Indexed: 12/11/2022]
Abstract
Food palatability produces behavioral modifications that resemble those induced by drugs of abuse. Palatability-induced behavioral changes require both, the activation of the endogenous cannabinoid system, and changes in structural plasticity in neurons of the brain reward pathway. The ERK intracellular pathway is activated by CB1 receptors (CB1-R) and plays a crucial role in neuroplasticity. We investigated the activation of the ERK signaling cascade in the mesocorticolimbic system induced by operant training to obtain highly palatable isocaloric food and the involvement of the CB1-R in these responses. Using immunofluorescence techniques, we analyzed changes in ERK intracellular pathway activation in the mesocorticolimbic system of wild-type and CB1 knockout mice (CB1-/-) trained on an operant paradigm to obtain standard, highly caloric or highly palatable isocaloric food. Operant training for highly palatable isocaloric food, but not for standard or highly caloric food, produced a robust activation of the ERK signaling cascade in the same brain areas where this training modified structural plasticity. These changes induced by the operant training were absent in CB1-/-. We can conclude that the activation of the ERK pathway is associated to the neuroplasticity induced by operant training for highly palatable isocaloric food and might be involved in CB1-R mediated alterations in behavior and structural plasticity.
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Affiliation(s)
- Thomas Guegan
- Laboratori de Neurofarmacologia, Univeristat Pompeu Fabra, PRBB, Barcelona, Spain
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Li S, Li Z, Pei L, Le AD, Liu F. The α7nACh-NMDA receptor complex is involved in cue-induced reinstatement of nicotine seeking. ACTA ACUST UNITED AC 2012; 209:2141-7. [PMID: 23091164 PMCID: PMC3501362 DOI: 10.1084/jem.20121270] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Smoking is the leading preventable cause of disease, disability, and premature death. Nicotine, the main psychoactive drug in tobacco, is one of the most heavily used addictive substances, and its continued use is driven through activation of nicotinic acetylcholine receptors (nAChRs). Despite harmful consequences, it is difficult to quit smoking because of its positive effects on mood and cognition that are strong reinforcers contributing to addiction. Furthermore, a formidable challenge for the treatment of nicotine addiction is the high vulnerability to relapse after abstinence. There is no currently available smoking cessation product able to achieve a >20% smoking cessation rate after 52 wk, and there are no medications that directly target the relapse process. We report here that the α7nAChR forms a protein complex with the NMDA glutamate receptor (NMDAR) through a direct protein-protein interaction. Chronic nicotine exposure promotes α7nAChR-NMDAR complex formation. Interestingly, administration of an interfering peptide that disrupts the α7nAChR-NMDAR complex decreased extracellular signal-regulated kinase (ERK) activity and blocked cue-induced reinstatement of nicotine seeking in rat models of relapse, without affecting nicotine self-administration or locomotor activity. Our results may provide a novel therapeutic target for the development of medications for preventing nicotine relapse.
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Affiliation(s)
- Shupeng Li
- Department of Neuroscience, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario M5T 1R8, Canada
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16
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Xu Y, Lv XF, Cui CL, Ge FF, Li YJ, Zhang HL. Essential role of NR2B-containing NMDA receptor-ERK pathway in nucleus accumbens shell in morphine-associated contextual memory. Brain Res Bull 2012; 89:22-30. [PMID: 22776695 DOI: 10.1016/j.brainresbull.2012.06.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 06/06/2012] [Accepted: 06/29/2012] [Indexed: 11/16/2022]
Abstract
Learned associations between the rewarding effect of addictive drugs and drug-paired contexts resist extinction and contribute to the high rate of relapse observed in drug addicts. Although it has been shown that extracellular signal-regulated kinase 1/2 (ERK1/2) activity in the nucleus accumbens (NAc) is modulated by the primary rewarding effect of opiates, little is known as to its role in the morphine-associated contextual memory. In the present study, we investigated the ERK1/2 activity indicated by phosphorylated ERK1/2 (pERK1/2) levels in rats using a morphine-induced conditioned place preference (CPP) procedure. Our results showed that, in rats that had undergone morphine conditioning, after testing (expression phase) pERK1/2 in the NAc shell but not the NAc core or the adjacent caudate putamen was specifically increased. pERK1/2 levels in several other parts of the brain involved in drug-seeking, such as the medial prefrontal cortex, dorsal hippocampus, and basolateral amygdala, showed no significant changes. A significant positive correlation was observed between the elevated pERK1/2 level in the NAc shell and the degree of conditioned preference for morphine-associated contexts. Bilateral injection of an inhibitor of ERK activation into the NAc shell attenuated ERK1/2 phosphorylation and prevented the expression of morphine CPP, but injections into the core did not. Selective inhibition of NR2B-containing NMDA receptor in the NAc shell by ifenprodil prevented CPP expression and down-regulated local ERK1/2 phosphorylation. These findings collectively suggest that recall of morphine-associated contextual memory depends specifically upon ERK1/2 activation in the NAc shell and that ERK1/2 phosphorylation is regulated by the upstream NR2B-containing NMDA receptor.
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Affiliation(s)
- Ya Xu
- Neuroscience Research Institute, Peking University, Beijing, PR China
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17
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Allen PJ, Batra P, Geiger BM, Wommack T, Gilhooly C, Pothos EN. Rationale and consequences of reclassifying obesity as an addictive disorder: neurobiology, food environment and social policy perspectives. Physiol Behav 2012; 107:126-37. [PMID: 22583861 DOI: 10.1016/j.physbeh.2012.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 04/02/2012] [Accepted: 05/06/2012] [Indexed: 01/13/2023]
Abstract
The rapid increase in the prevalence of obesity is a priority for investigators from across numerous disciplines, including biology, nutritional science, and public health and policy. In this paper, we systematically examine the premise that common dietary obesity is an addictive disorder, based on the criteria for addiction described in the Diagnostic and Statistical Manual (DSM) of Mental Disorders of the American Psychiatric Association, version IV, and consider the consequences of such a reclassification of obesity for public policy. Specifically, we discuss evidence from both human and animal studies investigating the effects of various types and amounts of food and the food environment in obese individuals. Neurobiological studies have shown that the hedonic brain pathways activated by palatable food overlap considerably with those activated by drugs of abuse and suffer significant deficits after chronic exposure to high-energy diets. Furthermore, food as a stimulus can induce the sensitization, compulsion and relapse patterns observed in individuals who are addicted to illicit drugs. The current food environment encourages these addictive-like behaviors where increased exposure through advertisements, proximity and increased portion sizes are routine. Taking lessons from the tobacco experience, it is clear that reclassifying common dietary obesity as an addictive disorder would necessitate policy changes (e.g., regulatory efforts, economic strategies, and educational approaches). These policies could be instrumental in addressing the obesity epidemic, by encouraging the food industry and the political leadership to collaborate with the scientific and medical community in establishing new and more effective therapeutic approaches.
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Affiliation(s)
- Patricia J Allen
- Department of Psychology, Tufts University, Medford, MA 02155, USA
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18
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Zheng W, Ycu EA. A fully automated and highly versatile system for testing multi-cognitive functions and recording neuronal activities in rodents. J Vis Exp 2012:e3685. [PMID: 22588124 DOI: 10.3791/3685] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We have developed a fully automated system for operant behavior testing and neuronal activity recording by which multiple cognitive brain functions can be investigated in a single task sequence. The unique feature of this system is a custom-made, acoustically transparent chamber that eliminates many of the issues associated with auditory cue control in most commercially available chambers. The ease with which operant devices can be added or replaced makes this system quite versatile, allowing for the implementation of a variety of auditory, visual, and olfactory behavioral tasks. Automation of the system allows fine temporal (10 ms) control and precise time-stamping of each event in a predesigned behavioral sequence. When combined with a multi-channel electrophysiology recording system, multiple cognitive brain functions, such as motivation, attention, decision-making, patience, and rewards, can be examined sequentially or independently.
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Affiliation(s)
- Weimin Zheng
- The Neurosciences Institute, San Diego, CA, USA.
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19
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Abstract
Although the term 'epigenetics' was coined nearly seventy years ago, its critical function in memory processing by the adult CNS has only recently been appreciated. The hypothesis that epigenetic mechanisms regulate memory and behavior was motivated by the need for stable molecular processes that evade turnover of the neuronal proteome. In this article, we discuss evidence that supports a role for neural epigenetic modifications in the formation, consolidation and storage of memory. In addition, we will review the evidence that epigenetic mechanisms regulate synaptic plasticity, a cellular correlate of memory. We will also examine how the concerted action of multiple epigenetic mechanisms with varying spatiotemporal profiles influence selective gene expression in response to behavioral experience. Finally, we will suggest key areas for future research that will help elucidate the complex, vital and still mysterious, role of epigenetic mechanisms in neural function and behavior.
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Affiliation(s)
- Faraz A Sultan
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F McKnight Brain Institute, 1007 Shelby Building, 1825 University Boulevard Birmingham, AL 35294-2182, USA
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20
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Besheer J, Fisher KR, Cannady R, Grondin JJM, Hodge CW. Intra-amygdala inhibition of ERK(1/2) potentiates the discriminative stimulus effects of alcohol. Behav Brain Res 2011; 228:398-405. [PMID: 22209853 DOI: 10.1016/j.bbr.2011.12.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 12/08/2011] [Accepted: 12/14/2011] [Indexed: 01/11/2023]
Abstract
Extracellular signal-regulated kinase (ERK(1/2)) has been implicated in modulating drug seeking behavior and is a target of alcohol and other drugs of abuse. Given that the discriminative stimulus (subjective/interoceptive) effects of drugs are determinants of abuse liability and can influence drug seeking behavior, we examined the role of ERK(1/2) in modulating the discriminative stimulus effects of alcohol. Using drug discrimination procedures, rats were trained to discriminate a moderate intragastric (IG) alcohol dose (1g/kg) versus water (IG). Following an alcohol (1g/kg) discrimination session phosphorylated ERK(1/2) (pERK(1/2)) immunoreactivity (IR) was significantly elevated in the amygdala, but not the nucleus accumbens. Therefore, we hypothesized that intra-amygdala inhibition of ERK(1/2) would disrupt expression of the discriminative stimulus effects of alcohol. However, intra-amygdala or accumbens administration of the MEK/ERK(1/2) inhibitor U0126 (1 and 3μg) had no effect on the discriminative stimulus effects of the training dose of alcohol (1g/kg). Contrary to our hypothesis, intra-amygdala infusion of U0126 (3μg) potentiated the discriminative stimulus effects of a low alcohol dose (0.5g/kg) and had no effect following nucleus accumbens infusion. Importantly, site-specific inhibition of pERK(1/2) in each brain region was confirmed. Therefore, the increase in pERK(1/2) IR in the amygdala following systemic alcohol administration may be reflective of the widespread effects of alcohol on the brain (activation/inhibition of brain circuits), whereas the site specific microinjection studies confirmed functional involvement of intra-amygdala ERK(1/2). These findings show that activity of the ERK signaling pathway in the amygdala can influence the discriminative stimulus effects of alcohol.
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Affiliation(s)
- Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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21
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Shiflett MW, Balleine BW. Molecular substrates of action control in cortico-striatal circuits. Prog Neurobiol 2011; 95:1-13. [PMID: 21704115 PMCID: PMC3175490 DOI: 10.1016/j.pneurobio.2011.05.007] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 05/24/2011] [Accepted: 05/27/2011] [Indexed: 11/24/2022]
Abstract
The purpose of this review is to describe the molecular mechanisms in the striatum that mediate reward-based learning and action control during instrumental conditioning. Experiments assessing the neural bases of instrumental conditioning have uncovered functional circuits in the striatum, including dorsal and ventral striatal sub-regions, involved in action-outcome learning, stimulus-response learning, and the motivational control of action by reward-associated cues. Integration of dopamine (DA) and glutamate neurotransmission within these striatal sub-regions is hypothesized to enable learning and action control through its role in shaping synaptic plasticity and cellular excitability. The extracellular signal regulated kinase (ERK) appears to be particularly important for reward-based learning and action control due to its sensitivity to combined DA and glutamate receptor activation and its involvement in a range of cellular functions. ERK activation in striatal neurons is proposed to have a dual role in both the learning and performance factors that contribute to instrumental conditioning through its regulation of plasticity-related transcription factors and its modulation of intrinsic cellular excitability. Furthermore, perturbation of ERK activation by drugs of abuse may give rise to behavioral disorders such as addiction.
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22
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Abstract
Although the critical role for epigenetic mechanisms in development and cell differentiation has long been appreciated, recent evidence reveals that these mechanisms are also employed in postmitotic neurons as a means of consolidating and stabilizing cognitive-behavioral memories. In this review, we discuss evidence for an "epigenetic code" in the central nervous system that mediates synaptic plasticity, learning, and memory. We consider how specific epigenetic changes are regulated and may interact with each other during memory formation and how these changes manifest functionally at the cellular and circuit levels. We also describe a central role for mitogen-activated protein kinases in controlling chromatin signaling in plasticity and memory. Finally, we consider how aberrant epigenetic modifications may lead to cognitive disorders that affect learning and memory, and we review the therapeutic potential of epigenetic treatments for the amelioration of these conditions.
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Affiliation(s)
- Jeremy J Day
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
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23
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Edwards S, Bachtell RK, Guzman D, Whisler KN, Self DW. Emergence of context-associated GluR(1) and ERK phosphorylation in the nucleus accumbens core during withdrawal from cocaine self-administration. Addict Biol 2011; 16:450-7. [PMID: 21309958 DOI: 10.1111/j.1369-1600.2010.00296.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reexposure to cocaine-associated environments promotes relapse to cocaine seeking and represents a persistent impediment to successful abstinence. Neurobiological adaptations are thought to underlie the preservation of drug-seeking behavior during protracted withdrawal periods, possibly including changes associated specifically with cocaine-paired contexts. We measured GluR(1) (S845) and extracellular signal-regulated kinase (ERK) phosphorylation in rat striatal subregions in an animal model of cocaine relapse. Animals with cocaine self-administration experience and their yoked partners were exposed to extinction conditions for one hour in the drug-paired environmental context after one day or three weeks withdrawal to measure protein phosphorylation induced by the cocaine-paired context in the absence of cocaine reinforcement. GluR(1) (S845) (an index of protein kinase A (PKA) activity) and ERK phosphorylation increased in the nucleus accumbens core of self-administering but not yoked animals after three weeks (but not one day) withdrawal, indicating a time-dependent emergence of context-associated protein phosphorylation in this accumbens subregion. In comparison, animals trained to self-administer sucrose displayed a similar increase in ERK, but not GluR(1) (S845) , phosphorylation following reexposure to a sucrose-paired environment three weeks later, indicating that GluR(1) (S845) phosphorylation did not result solely from lever press behavior per se. In contrast, basal (home cage) GluR(1) (S845) phosphorylation was elevated in the nucleus accumbens shell and caudate-putamen after one day or three weeks cocaine withdrawal regardless of context exposure. These results suggest that time-dependent emergence of context-associated GluR(1) (S845) phosphorylation in the nucleus accumbens core may contribute to the persistence of cocaine-seeking behavior, whereas ERK phosphorylation may be a consequence of this behavior.
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Affiliation(s)
- Scott Edwards
- Department of Psychiatry and Neuroscience Graduate Program, The Seay Center for Basic and Applied Research in Psychiatric Illness, UT Southwestern Medical Center, Dallas, TX 75390-9070, USA
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24
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Ito M, Doya K. Multiple representations and algorithms for reinforcement learning in the cortico-basal ganglia circuit. Curr Opin Neurobiol 2011; 21:368-73. [PMID: 21531544 DOI: 10.1016/j.conb.2011.04.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 04/07/2011] [Indexed: 10/18/2022]
Abstract
Accumulating evidence shows that the neural network of the cerebral cortex and the basal ganglia is critically involved in reinforcement learning. Recent studies found functional heterogeneity within the cortico-basal ganglia circuit, especially in its ventromedial to dorsolateral axis. Here we review computational issues in reinforcement learning and propose a working hypothesis on how multiple reinforcement learning algorithms are implemented in the cortico-basal ganglia circuit using different representations of states, values, and actions.
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Affiliation(s)
- Makoto Ito
- Neural Computation Unit, Okinawa Institute of Science and Technology, Okinawa 904-0412, Japan
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25
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Shiflett MW, Balleine BW. Contributions of ERK signaling in the striatum to instrumental learning and performance. Behav Brain Res 2010; 218:240-7. [PMID: 21147168 DOI: 10.1016/j.bbr.2010.12.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Accepted: 12/07/2010] [Indexed: 02/07/2023]
Abstract
The striatum is critical for learning and decision making; however, the molecular mechanisms that govern striatum function are not fully understood. The extracellular signal regulated kinase (ERK) cascade is an important signaling pathway that underlies synaptic plasticity, cellular excitability, learning and arousal. This review focuses on the role of ERK signaling in striatum function. ERK is activated in the striatum by coordinated dopamine and glutamate receptor signaling, where it underlies corticostriatal synaptic plasticity and influences striatal cell excitability. ERK activation in the dorsal striatum is necessary for action-outcome learning and performance of goal-directed actions. In the ventral striatum, ERK is necessary for the motivating effects of reward-associated stimuli on instrumental performance. Dysregulation of ERK signaling in the striatum by repeated drug exposure contributes to the development of addictive behavior. These results highlight the importance of ERK signaling in the striatum as a critical substrate for learning and as a regulator of ongoing behavior. Furthermore, they suggest that ERK may be a suitable target for therapeutics to treat disorders of learning and decision making that arise from compromised striatum function.
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Affiliation(s)
- Michael W Shiflett
- Department of Psychology, Rutgers University, 301 Smith Hall, 101 Warren St., Newark, NJ 07102, USA.
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26
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Shiflett MW, Brown RA, Balleine BW. Acquisition and performance of goal-directed instrumental actions depends on ERK signaling in distinct regions of dorsal striatum in rats. J Neurosci 2010; 30:2951-9. [PMID: 20181592 PMCID: PMC2844638 DOI: 10.1523/jneurosci.1778-09.2010] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 09/01/2009] [Accepted: 09/03/2009] [Indexed: 11/21/2022] Open
Abstract
The performance of goal-directed actions relies on an animal's previous knowledge of the outcomes or consequences that result from its actions. Additionally, a sensorimotor learning process linking environmental stimuli with actions influences instrumental performance by selecting actions for additional evaluation. These distinct decision-making processes in rodents depend on separate subregions of the dorsal striatum. Whereas the posterior dorsomedial striatum (pDMS) is required for the encoding of actions with their outcomes or consequences, the dorsolateral striatum (DLS) mediates action selection based on sensorimotor learning. However, the molecular mechanisms within these brain regions that support learning and performance of goal-directed behavior are not known. Here we show that activation of extracellular signal-regulated kinase (ERK) in the dorsal striatum has a critical role in learning and performance of instrumental goal-directed behavior in rodents. We observed an increase in p42 ERK (ERK2) activation in both the pDMS and DLS during both the acquisition and performance of recently acquired instrumental goal-directed actions. Furthermore, disruption of ERK activation in the pDMS prevented both the acquisition of action-outcome associations, as well as the performance of goal-directed actions guided by previously acquired associations, whereas disruption of ERK activation in the DLS disrupted instrumental performance but left instrumental action-outcome learning intact. These results provide evidence of a critical, region-specific role for ERK signaling in the dorsal striatum during the acquisition of instrumental learning and suggest that processes sensitive to ERK signaling within these striatal subregions interact to control instrumental performance after initial acquisition.
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Affiliation(s)
- Michael W Shiflett
- Department of Psychology, University of California, Los Angeles, Los Angeles, California 90095-1563, USA.
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27
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Shiflett MW, Mauna JC, Chipman AM, Peet E, Thiels E. Appetitive Pavlovian conditioned stimuli increase CREB phosphorylation in the nucleus accumbens. Neurobiol Learn Mem 2009; 92:451-4. [PMID: 19248836 DOI: 10.1016/j.nlm.2009.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 02/17/2009] [Accepted: 02/17/2009] [Indexed: 12/27/2022]
Abstract
The transcription factor cAMP response element-binding protein (CREB) in the nucleus accumbens (NAc) has been shown to regulate an animal's behavioral responsiveness to emotionally salient stimuli, and an increase in CREB phosphorylation in the NAc has been observed during exposure to rewarding stimuli, such as drugs of abuse. Here we show that CREB phosphorylation increases in the NAc also during exposure to cues that an animal has associated with delivery of natural rewards. Adult male Sprague-Dawley rats (rattus norvegicus) were trained to associate an auditory stimulus with delivery of food pellets, and CREB phosphorylation was examined in the striatum following training. We found that repeated tone-food pairings resulted in an increase in CREB phosphorylation in the NAc but not in the adjacent dorsal striatum or in the NAc 3h after the final training session. We further found that the cue itself, as opposed to the food pellets, the training context, or tone-food pairings, was sufficient to increase CREB phosphorylation in the NAc. These results suggest that the processing of primary rewarding stimuli and of environmental cues that predict them triggers similar accumbal signaling mechanisms.
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Affiliation(s)
- Michael W Shiflett
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
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28
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Central amygdala extracellular signal-regulated kinase signaling pathway is critical to incubation of opiate craving. J Neurosci 2009; 28:13248-57. [PMID: 19052216 DOI: 10.1523/jneurosci.3027-08.2008] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cue-induced drug-seeking in rodents progressively increases after withdrawal from operant self-administration of cocaine, heroin, methamphetamine, and alcohol, a phenomenon termed "incubation of drug craving." Here, we used the opiate drug morphine and explored whether incubation of drug craving also occurs in a pavlovian conditioned place preference (CPP) procedure in which rats learn to associate drug effects with a distinct environmental context. We also explored the role of amygdala extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB) in this incubation. We found that the expression of morphine CPP progressively increases over the first 14 d after the last drug exposure in rats receiving four pairings of low-dose (1 or 3 mg/kg) but not high-dose (10 mg/kg) morphine with a distinct environment. The progressive increase in low-dose (3 mg/kg) morphine CPP was associated with increased ERK phosphorylation (a measure of ERK activity) and CREB (a downstream target of ERK) phosphorylation in central but not basolateral amygdala. Furthermore, inhibition of central but not basolateral amygdala ERK and CREB phosphorylation by U0126 [1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto)butadiene] decreased the enhanced (incubated) drug CPP after 14 d of withdrawal from morphine. Finally, stimulation of central amygdala ERK and CREB phosphorylation by NMDA enhanced drug CPP after 1 d of withdrawal from morphine, an effect reversed by U0126. These findings indicate that the rat's response to environmental cues previously paired with morphine progressively increases or incubates over the first 14 d of withdrawal from low but not high morphine doses. Additionally, this "incubation of morphine craving" is mediated by acute activation of central amygdala ERK pathway.
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29
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Abstract
In associative learning, animals learn to associate external cues or their own actions with appetitive or aversive outcomes. Although the dopamine (DA) system and the striatum/nucleus accumbens have been implicated in both the pavlovian and instrumental form of associative learning, whether specific neuronal signaling mechanisms underlie one form or the other is unknown. Here, we report that the striatum-enriched isoform of adenylyl cyclase (AC), AC5, is selectively required for appetitive pavlovian learning. Mice with genetic deletion of AC5 (AC5KO) acquired instrumental responding yet were unable to use cues that predicted reward delivery. The specificity of this deficit was confirmed by an inability of AC5KO mice to learn a simple appetitive pavlovian conditioning task. Conversely, AC5KO mice showed intact aversive pavlovian learning, suggesting the deficit was specific for learning about appetitive outcomes. Our results suggest that AC5 is a critical component of DA-dependent strengthening of stimulus-reward contingencies.
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30
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Taylor JR, Olausson P, Quinn JJ, Torregrossa MM. Targeting extinction and reconsolidation mechanisms to combat the impact of drug cues on addiction. Neuropharmacology 2008; 56 Suppl 1:186-95. [PMID: 18708077 DOI: 10.1016/j.neuropharm.2008.07.027] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 07/11/2008] [Accepted: 07/20/2008] [Indexed: 02/01/2023]
Abstract
Drug addiction is a progressive and compulsive disorder, where recurrent craving and relapse to drug-seeking occur even after long periods of abstinence. A major contributing factor to relapse is drug-associated cues. Here we review behavioral and pharmacological studies outlining novel methods of effective and persistent reductions in cue-induced relapse behavior in animal models. We focus on extinction and reconsolidation of cue-drug associations as the memory processes that are the most likely targets for interventions. Extinction involves the formation of new inhibitory memories rather than memory erasure; thus, it should be possible to facilitate the extinction of cue-drug memories to reduce relapse. We propose that context-dependency of extinction might be altered by mnemonic agents, thereby enhancing the efficacy of cue-exposure therapy as treatment strategy. In contrast, interfering with memory reconsolidation processes can disrupt the integrity or strength of specific cue-drug memories. Reconsolidation is argued to be a distinct process that occurs over a brief time period after memory is reactivated/retrieved - when the memory becomes labile and vulnerable to disruption. Reconsolidation is thought to be an independent, perhaps opposing, process to extinction and disruption of reconsolidation has recently been shown to directly affect subsequent cue-drug memory retrieval in an animal model of relapse. We hypothesize that a combined approach aimed at both enhancing the consolidation of cue-drug extinction and interfering with the reconsolidation of cue-drug memories will have a greater potential for persistently inhibiting cue-induced relapse than either treatment alone.
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Affiliation(s)
- Jane R Taylor
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University School of Medicine, S307 Connecticut Mental Health Center, Ribicoff Research Laboratories, 34 Park Street, New Haven, CT 06508, USA.
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31
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Delayed, context- and dopamine D1 receptor-dependent activation of ERK in morphine-sensitized mice. Neuropharmacology 2008; 55:230-7. [PMID: 18614186 DOI: 10.1016/j.neuropharm.2008.05.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 05/19/2008] [Accepted: 05/19/2008] [Indexed: 11/22/2022]
Abstract
Exposure to cues previously associated with intake of substances of abuse can promote drug related responses. In this study, we have examined the effect of exposure to a drug-associated context on the expression of morphine psychomotor sensitization. We show that sensitization is markedly increased in mice examined 4 weeks after the last morphine injection. In addition, this incubation period confers to the environment paired with morphine the ability to increase ERK phosphorylation in the shell (but not the core) of the nucleus accumbens. Using transgenic mice with enhanced green fluorescent protein (EGFP) expression under the control of the dopamine D1 receptor (D1R) (Drd1a-EGFP) or D2 receptor promoter (Drd2-EGFP) we show that context-dependent ERK phosphorylation is restricted to D1R-expressing medium spiny neurons. Furthermore, this effect depends on D1R activation. These data show that, following repeated morphine injections, a drug-free period induces context-dependent phosphorylation of ERK in a specific population of neurons within the nucleus accumbens shell. This activation is associated to enhanced psychomotor sensitization and may be implicated in context-elicited drug seeking induced by repeated exposure to drugs of abuse.
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32
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Extracellular signal-related kinase activation during natural reward learning: a physiological role for phasic nucleus accumbens dopamine? J Neurosci 2008; 28:4295-7. [PMID: 18434506 DOI: 10.1523/jneurosci.0776-08.2008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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