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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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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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Amaral IM, Scheffauer L, Langeder AB, Hofer A, El Rawas R. Rewarding Social Interaction in Rats Increases CaMKII in the Nucleus Accumbens. Biomedicines 2021; 9:1886. [PMID: 34944702 PMCID: PMC8698734 DOI: 10.3390/biomedicines9121886] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 12/04/2022] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is known to be involved in the sensitized locomotor responses and drug-seeking behavior to psychostimulants. However, little is known about the contribution of CaMKII signaling in the nucleus accumbens (NAc) in natural rewards such as social interaction. The present experiments explored the implication of CaMKII signaling in drug versus natural reward. In the NAc of rats expressing cocaine or social interaction conditioned place preference (CPP), αCaMKII activation was induced in those expressing social interaction but not cocaine CPP. In order to investigate the role of NAc CaMKII in the expression of reward-related learning of drug versus non-drug stimuli, we inhibited CaMKII through an infusion of KN-93, a CaMKII inhibitor, directly into the NAc shell or core, before the CPP test in a concurrent paradigm in which social interaction was made available in the compartment alternative to the one associated with cocaine during conditioning. Whereas vehicle infusions led to equal preference to both stimuli, inhibition of CaMKII by a KN-93 infusion before the CPP test in the shell but not the core of the NAc shifted the rats' preference toward the cocaine-associated compartment. Altogether, these results suggest that social interaction reward engages CaMKII in the NAc.
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Affiliation(s)
| | | | | | | | - Rana El Rawas
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.M.A.); (L.S.); (A.B.L.); (A.H.)
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Amaral IM, Lemos C, Cera I, Dechant G, Hofer A, El Rawas R. Involvement of cAMP-Dependent Protein Kinase in the Nucleus Accumbens in Cocaine Versus Social Interaction Reward. Int J Mol Sci 2020; 22:E345. [PMID: 33396297 PMCID: PMC7794935 DOI: 10.3390/ijms22010345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/24/2020] [Accepted: 12/28/2020] [Indexed: 12/21/2022] Open
Abstract
Evidence suggests that PKA activity in the nucleus accumbens (NAc) plays an essential role in reward-related learning. In this study, we investigated whether PKA is differentially involved in the expression of learning produced by either natural reinforcers or psychostimulants. For that purpose, we inhibited PKA through a bilateral infusion of Rp-cAMPS, a specific PKA inhibitor, directly into the NAc. The effects of PKA inhibition in the NAc on the expression of concurrent conditioned place preference (CPP) for cocaine (drug) and social interaction (natural reward) in rats were evaluated. We found that PKA inhibition increased the expression of cocaine preference. This effect was not due to altered stress levels or decreased social reward. PKA inhibition did not affect the expression of natural reward as intra-NAc Rp-cAMPS infusion did not affect expression of social preference. When rats were trained to express cocaine or social interaction CPP and tested for eventual persisting preference 7 and 14 days after CPP expression, cocaine preference was persistent, but social preference was abolished after the first test. These results suggest that PKA in the NAc is involved in drug reward learning that might lead to addiction and that only drug, but not natural, reward is persistent.
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Affiliation(s)
- Inês M. Amaral
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.M.A.); (C.L.); (A.H.)
| | - Cristina Lemos
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.M.A.); (C.L.); (A.H.)
| | - Isabella Cera
- Institute for Neuroscience, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.C.); (G.D.)
| | - Georg Dechant
- Institute for Neuroscience, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.C.); (G.D.)
| | - Alex Hofer
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.M.A.); (C.L.); (A.H.)
| | - Rana El Rawas
- Division of Psychiatry I, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, 6020 Innsbruck, Austria; (I.M.A.); (C.L.); (A.H.)
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Kardos J, Dobolyi Á, Szabó Z, Simon Á, Lourmet G, Palkovits M, Héja L. Molecular Plasticity of the Nucleus Accumbens Revisited-Astrocytic Waves Shall Rise. Mol Neurobiol 2019; 56:7950-7965. [PMID: 31134458 PMCID: PMC6834761 DOI: 10.1007/s12035-019-1641-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/06/2019] [Indexed: 12/11/2022]
Abstract
Part of the ventral striatal division, the nucleus accumbens (NAc) drives the circuit activity of an entire macrosystem about reward like a "flagship," signaling and leading diverse conducts. Accordingly, NAc neurons feature complex inhibitory phenotypes that assemble to process circuit inputs and generate outputs by exploiting specific arrays of opposite and/or parallel neurotransmitters, neuromodulatory peptides. The resulting complex combinations enable versatile yet specific forms of accumbal circuit plasticity, including maladaptive behaviors. Although reward signaling and behavior are elaborately linked to neuronal circuit activities, it is plausible to propose whether these neuronal ensembles and synaptic islands can be directly controlled by astrocytes, a powerful modulator of neuronal activity. Pioneering studies showed that astrocytes in the NAc sense citrate cycle metabolites and/or ATP and may induce recurrent activation. We argue that the astrocytic calcium, GABA, and Glu signaling and altered sodium and chloride dynamics fundamentally shape metaplasticity by providing active regulatory roles in the synapse- and network-level flexibility of the NAc.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary.
| | - Árpád Dobolyi
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Pázmány Péter sétány 1C, Budapest, 1117, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Guillaume Lourmet
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
| | - Miklós Palkovits
- Human Brain Tissue Bank, Semmelweis University, Tűzoltó utca 58, Budapest, H-1094, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
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Cortical thinness and volume differences associated with marijuana abuse in emerging adults. Drug Alcohol Depend 2015; 155:275-83. [PMID: 26249265 PMCID: PMC4581973 DOI: 10.1016/j.drugalcdep.2015.06.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/14/2015] [Accepted: 06/09/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND The prevalence of marijuana (MJ) use among youth and its legalization for medical or recreational use has intensified public health endeavors of understanding MJ effects on brain structure and function. Studies indicate that MJ use is related to impaired cognitive performance, and altered functional brain activation and chemistry in adolescents and adults, but MJ effects on brain morphology in emerging adults are less understood. METHODS Fifteen MJ users (age 21.8±3.6, 2 females) and 15 non-user (NU) participants (age 22.3±3.5, 2 females) were included, demographically matched on age, education and alcohol use. High-resolution structural MR images were acquired at 3Tesla. Cortical thickness (CT) and volumetric analyses were performed using Freesurfer. A priori regions of interest (ROI) included orbitofrontal and cingulate cortices, amygdala, hippocampus and thalamus. RESULTS Whole brain CT analysis did not result in significant group differences in a priori ROIs but revealed MJ users had significantly less CT (i.e., thinness) in right fusiform gyrus (rFG) compared to NU (p<0.05). Thalamic volume was significantly smaller in MJ users compared to NU (right, p=0.05; left, p=0.01) and associated with greater non-planning (p<0.01) and overall impulsivity (p=0.04). There were no other group differences. CONCLUSIONS RFG cortical thinness and smaller thalamic volume in emerging adults is associated with MJ abuse. Furthermore, smaller thalamic volume associated with greater impulsivity contributes to growing evidence that the thalamus is neurobiologically perturbed by MJ use. Collectively, altered thalamic and rFG structural integrity may interfere with their known roles in regulating visuoperceptual and object information processing.
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Baker TW, Florczynski MM, Beninger RJ. Differential effects of clozapine, metoclopramide, haloperidol and risperidone on acquisition and performance of operant responding in rats. Psychopharmacology (Berl) 2015; 232:1535-43. [PMID: 25381749 DOI: 10.1007/s00213-014-3789-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 10/20/2014] [Indexed: 10/24/2022]
Abstract
RATIONALE Prior research has not systematically investigated the effects of systemic antipsychotic drugs on operant response acquisition, specifically their behavioural microstructure, reinforcement blunting and relative potency in acquisition compared to performance once operant responding has stabilized. OBJECTIVES This study aims to systematically investigate the effects of systemically administered clozapine, metoclopramide, haloperidol and risperidone during free operant response acquisition and performance. METHODS Following magazine training, food-restricted male Wistar rats lever pressed for food reward in 15 min daily operant conditioning sessions. RESULTS All drugs suppressed operant response acquisition and performance. Risperidone and metoclopramide, but not clozapine or haloperidol, suppressed operant responding more potently during acquisition than performance. The dopamine D2-like receptor antagonists haloperidol and metoclopramide that affect the ventral and dorsal striatum blunted reinforcement and decreased inactive lever presses in acquisition. In contrast, the atypical antipsychotics clozapine and risperidone that affect the ventral striatum and prefrontal cortex failed to decrease inactive lever presses during acquisition, suggesting a possible decision-making deficit. Haloperidol decreased active lever pressing over performance days. The drugs did not appear to affect rats' sensitivity to active lever press outcome, even though they suppressed active lever pressing. CONCLUSIONS Results suggest that reinforcement impact during operant acquisition is dependent on dopamine D2 receptors while drugs affecting, among other areas, the prefrontal cortex produce a deficit in ability to suppress inactive lever press responses.
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Affiliation(s)
- Tyson W Baker
- Department of Psychology, Queen's University, 62 Arch St., Kingston, ON, K7L 3N6, Canada
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Hawkins RD, Byrne JH. Associative learning in invertebrates. Cold Spring Harb Perspect Biol 2015; 7:cshperspect.a021709. [PMID: 25877219 DOI: 10.1101/cshperspect.a021709] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This work reviews research on neural mechanisms of two types of associative learning in the marine mollusk Aplysia, classical conditioning of the gill- and siphon-withdrawal reflex and operant conditioning of feeding behavior. Basic classical conditioning is caused in part by activity-dependent facilitation at sensory neuron-motor neuron (SN-MN) synapses and involves a hybrid combination of activity-dependent presynaptic facilitation and Hebbian potentiation, which are coordinated by trans-synaptic signaling. Classical conditioning also shows several higher-order features, which might be explained by the known circuit connections in Aplysia. Operant conditioning is caused in part by a different type of mechanism, an intrinsic increase in excitability of an identified neuron in the central pattern generator (CPG) for feeding. However, for both classical and operant conditioning, adenylyl cyclase is a molecular site of convergence of the two signals that are associated. Learning in other invertebrate preparations also involves many of the same mechanisms, which may contribute to learning in vertebrates as well.
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Affiliation(s)
- Robert D Hawkins
- Department of Neuroscience, Columbia University, New York, New York 10032 New York State Psychiatric Institute, New York, New York 10032
| | - John H Byrne
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas 77030
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Abstract
The fetal or early origins of adult disease hypothesis states that environmental factors, particularly nutrition, act in early life to program the risks for chronic diseases in adult life. As eating habits can be linked to the development of several diseases including obesity, diabetes and cardiovascular disease, it could be proposed that persistent food preferences across the life-span in people who were exposed to an adverse fetal environment may partially explain their increased risk to develop metabolic disease later in life. In this paper, we grouped the clinical and experimental evidence demonstrating that the fetal environment may impact the individual's food preferences. In addition, we review the feeding preferences development and regulation (homeostatic and hedonic pathways, the role of taste/olfaction and the reward/pleasure), as well as propose mechanisms linking early life conditions to food preferences later in life. We review the evidence suggesting that in utero conditions are associated with the development of specific food preferences, which may be involved in the risk for later disease. This may have implications in terms of public health and primary prevention during early ages.
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8-pCPT, an Epac activator, impairs conditioned place preference based on nucleus accumbens amphetamine in rats. Acta Neuropsychiatr 2014; 26:104-11. [PMID: 24855888 DOI: 10.1017/neu.2013.37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Dopamine receptor-mediated 3',5'-cyclic adenosine monophosphate (cAMP)-dependent intracellular signalling is important for reward-related learning. cAMP activates cAMP-dependent protein kinase (PKA) and exchange protein directly activated by cAMP (Epac). We tested the hypothesis that reward-related learning may be mediated by Epac. METHODS We evaluated conditioned place preference (CPP) on the basis of nucleus accumbens (NAc) injections of amphetamine (20 μg/0.5 μl/side) plus Sp-adenosine 3',5'-cyclic monophosphorothioate triethylamanine (Sp-cAMPS) (0.1, 1.0, 10, 15, 20 μg/0.5 μl/side), an activator of both PKA and Epac, or amphetamine (20 μg) plus 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (8-pCPT) (0.73, 1.27, 1.45, 2.89, 5.78, 11.56 μg/0.5 μl/side), an activator of Epac. RESULTS In agreement with previous results, Sp-cAMPS dose-dependently impaired CPP. 8-pCPT impaired CPP at one dose (1.45 μg/0.5 μl/side) and we replicated this effect three times. CONCLUSION The results implicate Epac in the acquisition of reward-related learning.
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Portella AK, Silveira PP. Neurobehavioral determinants of nutritional security in fetal growth-restricted individuals. Ann N Y Acad Sci 2014; 1331:15-33. [DOI: 10.1111/nyas.12390] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- André Krumel Portella
- Hospital da Criança Santo Antônio; Santa Casa de Misericórdia de Porto Alegre; Rio Grande do Sul; Brazil
| | - Patrícia Pelufo Silveira
- Departamento de Pediatria, Faculdade de Medicina; Universidade Federal do Rio Grande do Sul; Rio Grande do Sul; Brazil
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Ávila-Ruiz T, Carranza V, Gustavo LL, Limón DI, Martínez I, Flores G, Flores-Hernández J. Chronic administration of nicotine enhances NMDA-activated currents in the prefrontal cortex and core part of the nucleus accumbens of rats. Synapse 2014; 68:248-56. [PMID: 24549882 DOI: 10.1002/syn.21726] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 10/22/2013] [Accepted: 10/28/2013] [Indexed: 12/28/2022]
Abstract
Nicotine is an addictive substance of tobacco. It has been suggested that nicotine acts on glutamatergic (N-methyl-d-aspartate, NMDA) neurotransmission affecting dopamine release in the mesocorticolimbic system. This effect is reflected in neuroadaptative changes that can modulate neurotransmission in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) core (cNAcc) and shell (sNAcc) regions. We evaluated the effect of chronic administration of nicotine (4.23 mg/kg/day for 14 days) on NMDA activated currents in dissociated neurons from the PFC, and NAcc (from core and shell regions). We assessed nicotine blood levels by mass spectrophotometry and we confirmed that nicotine increases locomotor activity. An electrophysiological study showed an increase in NMDA currents in neurons from the PFC and core part of the NAcc in animals treated with nicotine compared to those of control rats. No change was observed in neurons from the shell part of the NAcc. The enhanced glutamatergic activity observed in the neurons of rats with chronic administration of nicotine may explain the increased locomotive activity also observed in such rats. To assess one of the possible causes of increased NMDA currents, we used magnesium, to block NMDA receptor that contains the NR2B subunit. If there is a change in percent block of NMDA currents, it means that there is a possible change in expression of NMDA receptor subunits. Our results showed that there is no difference in the blocking effect of magnesium on the NMDA currents. The magnesium lacks of effect after nicotinic treatment suggests that there is no change in expression of NR2B subunit of NMDA receptors, then, the effect of nicotine treatment on amplitude of NMDA currents may be due to an increase in the quantity of receptors or to a change in the unitary conductance, rather than a change in the expression of the subunits that constitute it.
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Affiliation(s)
- Tania Ávila-Ruiz
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, CP 72570, Puebla, Puebla, México
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Chagniel L, Bergeron Y, Bureau G, Massicotte G, Cyr M. Regulation of tyrosine phosphatase STEP61 by protein kinase A during motor skill learning in mice. PLoS One 2014; 9:e86988. [PMID: 24466306 PMCID: PMC3900697 DOI: 10.1371/journal.pone.0086988] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 12/19/2013] [Indexed: 11/18/2022] Open
Abstract
Recently, striatal-enriched protein tyrosine phosphatase (STEP) and its upstream regulator protein kinase A (PKA) have been suspected to play a role in the intracellular mechanisms of fear conditioning and spatial memory. However, whether they contribute to the learning and memory of motor skills is totally unknown. In this study, we have investigated the role of STEP and PKA activities during motor skill learning associated with the accelerating rotarod task. We observed that learning the rotarod task differentially modulated the levels of phosphorylated STEP61 at serine 221, a site directly regulated by PKA, in the hippocampus, motor cortex and striatum. In a second set of experiments, we have pharmacologically inhibited PKA by the injection of Rp-cAMPS directly into the dorsal striatum of mice before rotarod trainings. PKA phosphorylation of STEP prevents the dephosphorylation of STEP substrates, whereas inhibition of PKA promotes STEP activity. Striatal PKA inhibitions dose-dependently impaired mice performances on the accelerating rotarod task. General motor abilities testing revealed an intact motor control in mice treated with 5 and 20 µg of Rp-cAMPS, but not at the highest dose of 40 µg. This suggested that motor learning was selectively affected by PKA inhibition at lower doses. Most notably, striatal inhibition of PKA reduced the levels of phosphorylated STEP61 at serine 221. Our data support that inactivation of STEP61 by the PKA activity is part of the molecular process associated with motor skill learning.
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Affiliation(s)
- Laure Chagniel
- Groupe de recherche en Neurosciences, Département de biologie médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Yan Bergeron
- Groupe de recherche en Neurosciences, Département de biologie médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Geneviève Bureau
- Groupe de recherche en Neurosciences, Département de biologie médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Guy Massicotte
- Groupe de recherche en Neurosciences, Département de biologie médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Michel Cyr
- Groupe de recherche en Neurosciences, Département de biologie médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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The clinical relevance of neuroplasticity in corticostriatal networks during operant learning. Neurosci Biobehav Rev 2013; 37:2071-80. [PMID: 23567518 DOI: 10.1016/j.neubiorev.2013.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/14/2013] [Accepted: 03/27/2013] [Indexed: 11/23/2022]
Abstract
Dopamine and glutamate serve crucial functions in neural plasticity, learning and memory, and addiction. Contemporary theories contend that these two, widely-distributed neurotransmitter systems play an integrative role in motivational and associative information processing. Combined signaling of these systems, particularly through the dopamine (DA) D1 and glutamate (Glu) N-methyl-d-aspartate receptors (NMDAR), triggers critical intracellular signaling cascades that lead to changes in chromatin structure, gene expression, synaptic plasticity, and ultimately behavior. Addictive drugs also induce long-term neuroadaptations at the molecular and genomic levels causing structural changes that alter basic connectivity. Indeed, evidence that drugs of abuse engage D1- and NMDA-mediated neuronal cascades shared with normal reward learning provides one of the most important insights from contemporary studies on the neurobiology of addiction. Such drug-induced neuroadaptations likely contribute to abnormal information processing and behavior, resulting in the poor decision-making, loss of control, and compulsivity that characterize addiction. Such features are also common to many other neuropsychiatric disorders. Behavior problems, construed as difficulties associated with operant learning and behavior, present compelling challenges and unique opportunities for their treatment that require further study. The present review highlights the integrative work of Ann E. Kelley and colleagues, demonstrating a critical role not only for NMDAR, D1 receptors (D1R), and their associated signaling cascades, but also for other Glu receptors and protein synthesis in operant learning throughout a cortico-striatal-limbic network. Recent work has extended the impact of appetitive learning to epigenetic processes. A better understanding of these processes will likely assist in discovering therapeutics to engage neural plasticity-related processes and promote functional behavioral adaptations.
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Effects of protein kinase A inhibitor and activator on rewarding effects of SKF-82958 microinjected into nucleus accumbens shell of ad libitum fed and food-restricted rats. Psychopharmacology (Berl) 2012; 221:589-99. [PMID: 22143580 PMCID: PMC3310955 DOI: 10.1007/s00213-011-2602-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Accepted: 11/27/2011] [Indexed: 10/14/2022]
Abstract
RATIONALE Previous studies indicate that the rewarding effect of D-1 dopamine receptor stimulation in nucleus accumbens (NAc) shell is greater in food-restricted (FR) than in ad libitum fed (AL) rats. The D-1 receptor is positively coupled to adenylyl cyclase and activates protein kinase A (PKA). OBJECTIVES The purpose of this study was to determine whether PKA is involved in the rewarding effect of D-1 receptor stimulation and, if so, whether it is involved in the enhanced response of FR rats. MATERIALS AND METHODS Rats were stereotaxically implanted with microinjection cannulae in NAc shell and a stimulating electrode in lateral hypothalamus. The rewarding effects of SKF-82958 (1.5 or 3.0 μg, bilaterally) in the presence and absence of PKA inhibitor, Rp-cAMPS (8.9 μg), and PKA activator, Sp-cAMPS (8.9 μg), were assessed using the curve-shift method of intracranial self-stimulation (ICSS). Basal NAc levels of DARPP-32 phosphorylated on Thr34 and Thr75 were measured. RESULTS Rp-cAMPS increased the rewarding effect of SKF-82958 in AL but not FR rats, doubling the ICSS threshold-lowering effect of the 3.0-μg dose. Sp-cAMPS decreased the rewarding effect of SKF-82958 in FR but not AL rats. Levels of phospho-DARPP-32 (Thr75), which inhibits PKA, were higher in FR than AL rats. CONCLUSIONS Results indicate that inhibition of PKA enhances the unconditioned rewarding effect of D-1 receptor stimulation and that decreased PKA may be involved in the effect of FR on drug reward. Evidence for involvement of D-2 receptor-expressing neurons in the enhancing effect of PKA inhibition is discussed.
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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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Davis MM, Olausson P, Greengard P, Taylor JR, Nairn AC. Regulator of calmodulin signaling knockout mice display anxiety-like behavior and motivational deficits. Eur J Neurosci 2012; 35:300-8. [PMID: 22250817 DOI: 10.1111/j.1460-9568.2011.07956.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Regulator of calmodulin (CaM) signaling (RCS), when phosphorylated by protein kinase A (PKA) on Ser55, binds to CaM and inhibits CaM-dependent signaling. RCS expression is high in the dorsal striatum, nucleus accumbens and amygdala, suggesting that the protein is involved in limbic-striatal function. To test this hypothesis, we examined RCS knockout (KO) mice in behavioral models dependent on these brain areas. Mice were tested for food-reinforced instrumental conditioning and responding under a progressive ratio (PR) schedule of reinforcement and in models of anxiety (elevated plus maze and open field). While RCS KO mice showed normal acquisition of a food-motivated instrumental response, they exhibited a lower breakpoint value when tested on responding under a PR schedule of reinforcement. RCS KO mice also displayed decreased exploration in both the open arms of an elevated plus maze and in the center region of an open field, suggesting an enhanced anxiety response. Biochemical studies revealed a reduction in the levels of dopamine and cAMP-regulated phosphoprotein (DARPP-32) in the striatum of RCS KO mice. DARPP-32 is important in reward-mediated behavior, suggestive of a possible role for DARPP-32 in mediating some of the effects of RCS. Together these results implicate a novel PKA-regulated phosphoprotein, RCS, in the etiology of motivational deficits and anxiety.
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Affiliation(s)
- Maya M Davis
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06508, USA
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18
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Cui H, Mason BL, Lee C, Nishi A, Elmquist JK, Lutter M. Melanocortin 4 receptor signaling in dopamine 1 receptor neurons is required for procedural memory learning. Physiol Behav 2012; 106:201-10. [PMID: 22342812 DOI: 10.1016/j.physbeh.2012.01.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 01/24/2012] [Accepted: 01/25/2012] [Indexed: 11/24/2022]
Abstract
It is now widely recognized that exposure to palatable foods engages reward circuits that promote over-eating and facilitate the development of obesity. While the melanocortin 4 receptor (MC4R) has previously been shown to regulate food intake and energy expenditure, little is known about its role in food reward. We demonstrate that MC4R is co-expressed with the dopamine 1 receptor (D1R) in the ventral striatum. While MC4R-null mice are hyperphagic and obese, they exhibit impairments in acquisition of operant responding for a high fat reinforcement. Restoration of MC4R signaling in D1R neurons normalizes procedural learning without affecting motivation to obtain high fat diet. MC4R signaling in D1R neurons is also required for learning in a non-food-reinforced version of the cued water maze. Finally, MC4R signaling in neostriatal slices increases phosphorylation of the Thr34 residue of DARPP-32, a protein phosphatase-1 inhibitor that regulates synaptic plasticity. These data identify a novel requirement for MC4R signaling in procedural memory learning.
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Affiliation(s)
- Huxing Cui
- Department of Internal Medicine (Division of Hypothalamic Research), University of Texas Southwestern Medical Center Dallas, Dallas, TX 75390-9127, United States
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Disrupting effect of drug-induced reward on spatial but not cue-guided learning: implication of the striatal protein kinase A/cAMP response element-binding protein pathway. J Neurosci 2012; 31:16517-28. [PMID: 22090478 DOI: 10.1523/jneurosci.1787-11.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The multiple memory systems hypothesis posits that different neural circuits function in parallel and may compete for information processing and storage. For example, instrumental conditioning would depend on the striatum, whereas spatial memory may be mediated by a circuit centered on the hippocampus. However, the nature of the task itself is not sufficient to select durably one system over the other. In this study, we investigated the effects of natural and pharmacological rewards on the selection of a particular memory system during learning. We compared the effects of food- or drug-induced activation of the reward system on cue-guided versus spatial learning using a Y-maze discrimination task. Drug-induced reward severely impaired the acquisition of a spatial discrimination task but spared the cued version of the task. Immunohistochemical analysis of the phosphorylated form of the cAMP response element binding (CREB) protein and c-Fos expression induced by behavioral testing revealed that the spatial deficit was associated with a decrease of both markers within the hippocampus and the prefrontal cortex. In contrast, drug reward potentiated the cued learning-induced CREB phosphorylation within the dorsal striatum. Administration of the protein kinase A inhibitor 8-Bromo-adenosine-3',5'-cyclic monophosphorothioate Rp isomer (Rp-cAMPS) into the dorsal striatum before training completely reversed the drug-induced spatial deficit and restored CREB phosphorylation levels within the hippocampus and the prefrontal cortex. Therefore, drug-induced striatal hyperactivity may underlie the declarative memory deficit reported here. This mechanism could represent an important early step toward the development of addictive behaviors by promoting conditioning to the detriment of more flexible forms of memory.
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20
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Jonkman S, Everitt BJ. Dorsal and ventral striatal protein synthesis inhibition affect reinforcer valuation but not the consolidation of instrumental learning. Learn Mem 2011; 18:617-24. [PMID: 21921211 DOI: 10.1101/lm.2269911] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The evidence for a role of the striatum in the acquisition of uncued instrumental responding is ambiguous. It has been shown that post-session infusions of anisomycin into the core of the nucleus accumbens (NAcc) impaired instrumental acquisition, but pre-training lesions of the NAcc suggest that it is not necessary. Recently, we demonstrated that the infusion of anisomycin into the anterior cingulate cortex impaired instrumental acquisition indirectly through a taste aversion. Thus, we hypothesized that post-session anisomycin infusions into the NAcc affected instrumental acquisition through an effect on reinforcer valuation. For the dorsal striatum, both post-session infusions of anisomycin and pre-training lesion studies suggest that neither the dorsolateral nor the dorsomedial striatum is necessary for the acquisition of instrumental responding. However, it has not been attempted to block plasticity in both regions concurrently, and we hypothesized that both regions independently contribute to acquisition through goal-directed and habitual learning. In the current experiments, we first replicated the effect of unprotected post-session anisomycin infusions into the NAcc on instrumental acquisition. Subsequently, we investigated the effect of protein synthesis inhibition in the NAcc and dorsomedial and dorsolateral striatum concurrently on instrumental acquisition, critically controlling for effects on reinforcer valuation. The anisomycin infusions induced an aversive state, but did not affect instrumental acquisition.
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Affiliation(s)
- Sietse Jonkman
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom.
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21
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Gerdjikov TV, Baker TW, Beninger RJ. Amphetamine-induced enhancement of responding for conditioned reward in rats: interactions with repeated testing. Psychopharmacology (Berl) 2011; 214:891-9. [PMID: 21107536 DOI: 10.1007/s00213-010-2099-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 11/08/2010] [Indexed: 12/28/2022]
Abstract
RATIONALE The mesolimbic dopamine system underlies the ability of reward-related stimuli to control operant behavior. Previous work has shown that amphetamine potentiates operant responding for conditioned rewards (CRs). OBJECTIVES Here, we asked whether the profile of this amphetamine-produced potentiation changes with repeated CR presentation, i.e., as the CR is being extinguished. METHODS Amphetamine (0-1.0 mg/kg, i.p.), administered over four daily sessions using a Latin square design, dose-dependently increased lever pressing for a 'lights-off' stimulus previously paired with food in rats. RESULTS The amphetamine-produced enhancement of responding for CR was significantly modulated with repeated CR exposure: it was strongest on day 1 and became less pronounced in subsequent sessions whereas the CR effect persisted. In further experiments, rats receiving LiCl devaluation of the primary reward failed to show a significant reduction in the amphetamine-produced enhancement of responding for CR. CONCLUSIONS The nature of the dissociable effects of amphetamine on responding for CR versus the CR effect itself remains to be elucidated.
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Affiliation(s)
- Todor V Gerdjikov
- Department of Psychology, Queen's University, Kingston, ON, K7L 3N6, Canada.
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22
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Gourley SL, Lee AS, Howell JL, Pittenger C, Taylor JR. Dissociable regulation of instrumental action within mouse prefrontal cortex. Eur J Neurosci 2010; 32:1726-34. [PMID: 21044173 DOI: 10.1111/j.1460-9568.2010.07438.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Evaluation of the behavioral 'costs', such as effort expenditure relative to the benefits of obtaining reward, is a major determinant of goal-directed action. Neuroimaging evidence suggests that the human medial orbitofrontal cortex (mOFC) is involved in this calculation and thereby guides goal-directed and choice behavior, but this region's functional significance in rodents is unknown despite extensive work characterizing the role of the lateral OFC in cue-related response inhibition processes. We first tested mice with mOFC lesions in an instrumental reversal task lacking discrete cues signaling reinforcement; here, animals were required to shift responding based on the location of the reinforced aperture within the chamber. Mice with mOFC lesions acquired the reversal but failed to inhibit responding on the previously reinforced aperture, while mice with prelimbic prefrontal cortex lesions were unaffected. When tested on a progressive ratio schedule of reinforcement, mice with prelimbic cortical lesions were unable to maintain responding, resulting in declining response levels. Mice with mOFC lesions, by contrast, escalated responding. Neither lesion affected sensitivity to satiety-specific outcome devaluation or non-reinforcement (i.e. extinction), and neither had effects when placed after animals were trained on a progressive ratio response schedule. Lesions of the ventral hippocampus, which projects to the mOFC, resulted in similar response patterns, while lateral OFC and dorsal hippocampus lesions resulted in response acquisition, though not inhibition, deficits in an instrumental reversal. Our findings thus selectively implicate the rodent mOFC in braking reinforced goal-directed action when reinforcement requires the acquisition of novel response contingencies.
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Affiliation(s)
- Shannon L Gourley
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06508, USA
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23
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Bialy M, Kalata U, Nikolaev-Diak A, Nikolaev E. D1 receptors involved in the acquisition of sexual experience in male rats. Behav Brain Res 2010; 206:166-76. [DOI: 10.1016/j.bbr.2009.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 08/27/2009] [Accepted: 09/03/2009] [Indexed: 02/09/2023]
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24
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Loss of dendrite stabilization by the Abl-related gene (Arg) kinase regulates behavioral flexibility and sensitivity to cocaine. Proc Natl Acad Sci U S A 2009; 106:16859-64. [PMID: 19805386 DOI: 10.1073/pnas.0902286106] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adolescence is characterized by increased vulnerability to developing neuropsychiatric disorders and involves a period of prefrontal cortical dendritic refinement and synaptic pruning that culminates in cytoskeletal stabilization in adulthood. The Abl-related gene (Arg) acts through p190RhoGAP to inhibit the RhoA GTPase and stabilize cortical dendritic arbors beginning in adolescence. Cortical axons, dendrites, and synapses develop normally in Arg-deficient (arg(-/-)) mice, but adult dendrites destabilize and regress; thus, arg(-/-) mice present a model of adolescent-onset dendritic simplification. We show that arg(-/-) mice are impaired in a reversal task and that deficits are grossly exacerbated by low-dose cocaine administration. Although ventral prefrontal dopamine D2 receptor levels predict "perseverative" error counts in wild-type mice, no such relationship is found in arg(-/-) mice. Moreover, arg(-/-) mice are insensitive to the disruptive effects of the D2/D3 antagonist haloperidol in reversal but show normal sensitivity to its locomotor-depressant actions. Arg deficiency and orbitofrontal cortical Arg inhibition via STI-571 infusion also enhance the psychomotor stimulant actions of cocaine. These findings provide evidence that stabilization of dendritic structure beginning in adolescence is critical for the development of adaptive and flexible behavior after cocaine exposure.
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25
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Gourley SL, Wu FJ, Taylor JR. Corticosterone regulates pERK1/2 map kinase in a chronic depression model. Ann N Y Acad Sci 2009; 1148:509-14. [PMID: 19120149 DOI: 10.1196/annals.1410.076] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Neurotransmitter- or neurotrophin-regulated intracellular signaling in the hippocampus is hypothesized to contribute to depression and antidepressant (ADT) efficacy. Extracellular signal-regulated kinase 1/2 (ERK1/2) is downstream of several receptor types and regulates transcriptional activity of many targets; ERK1/2 may thereby influence mood and affect. Using a novel, ADT-sensitive depression model in mice, we show that prior corticosterone exposure decreases motivated behavior, sucrose consumption, and pERK1/2 in the dentate gyrus, but not in CA1/CA3. Notably, prefrontal cortical targets were also regulated. Our data suggest ADTs restore hippocampal pERK1/2 after stress-related insult, and potentially reveal a novel role for prefrontal neurotrophins in depressive-like symptomology.
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Affiliation(s)
- Shannon L Gourley
- Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut, USA
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26
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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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Lorenzetti FD, Baxter DA, Byrne JH. Molecular mechanisms underlying a cellular analog of operant reward learning. Neuron 2008; 59:815-28. [PMID: 18786364 DOI: 10.1016/j.neuron.2008.07.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Revised: 01/23/2008] [Accepted: 07/07/2008] [Indexed: 11/30/2022]
Abstract
Operant conditioning is a ubiquitous but mechanistically poorly understood form of associative learning in which an animal learns the consequences of its behavior. Using a single-cell analog of operant conditioning in neuron B51 of Aplysia, we examined second-messenger pathways engaged by activity and reward and how they may provide a biochemical association underlying operant learning. Conditioning was blocked by Rp-cAMP, a peptide inhibitor of PKA, a PKC inhibitor, and by expressing a dominant-negative isoform of Ca2+-dependent PKC (apl-I). Thus, both PKA and PKC were necessary for operant conditioning. Injection of cAMP into B51 mimicked the effects of operant conditioning. Activation of PKC also mimicked conditioning but was dependent on both cAMP and PKA, suggesting that PKC acted at some point upstream of PKA activation. Our results demonstrate how these molecules can interact to mediate operant conditioning in an individual neuron important for the expression of the conditioned behavior.
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Affiliation(s)
- Fred D Lorenzetti
- Department of Neurobiology and Anatomy, W.M. Keck Center for Neurobiology of Learning and Memory, The University of Texas Medical School at Houston, Houston, TX 77030, USA
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28
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Paredes DA, Cartford MC, Catlow BJ, Samec A, Avilas M, George A, Schlunck A, Small B, Bickford PC. Neurotransmitter release during delay eyeblink classical conditioning: role of norepinephrine in consolidation and effect of age. Neurobiol Learn Mem 2008; 92:267-82. [PMID: 18809505 DOI: 10.1016/j.nlm.2008.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 08/28/2008] [Accepted: 08/28/2008] [Indexed: 11/30/2022]
Abstract
Delay classical eyeblink conditioning (EBC) is an important model of associative, cerebellar-dependent learning. Norepinephrine (NE) plays a significant modulatory role in the acquisition of learning; however, other neurotransmitters are also involved. The goal was to determine whether NE, gamma-aminobutyric acid (GABA) and glutamate (GLU) release are observed in cerebellar cortex during EBC, and whether such release was selectively associated with training. Further studies examined the role of the beta-noradrenergic receptor in consolidation of the learned response by local infusion of propranolol at 5-120 min following training into the cerebellar cortex. In vivo microdialysis coupled to EBC was performed to examine neurotransmitter release. An increase in the extracellular level of NE was observed during EBC and was maximal on day 1 and diminished in amplitude with subsequent days of training. No changes in baseline NE release were observed in pseudoconditioning indicating that NE release is directly related to the associative learning process. The extracellular levels of GABA were also increased selectively during paired training however, the magnitude of GABA release increased over days of training. GLU release was observed to increase during both paired and unpaired training, suggesting that learning does not occur prior to the information arriving in the cerebellum. When propranolol was administered at either 5-, 60-, or 120-min post-training, there was an inhibition of conditioned responses, these data support the hypothesis that NE is important for consolidation of learning. In another set of experiments we demonstrate that the timing of release of NE, GABA and glutamate are significantly delayed in onset and lengthened in duration in the 22-month-old F344 rats. Over days of training the timing of release becomes closer to the timing of training and this is associated with increased learning of conditioned responses in the aged rats.
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Affiliation(s)
- D A Paredes
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery, University of South Florida, Tampa, FL 33612, USA
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Parallel and interactive learning processes within the basal ganglia: relevance for the understanding of addiction. Behav Brain Res 2008; 199:89-102. [PMID: 18950658 DOI: 10.1016/j.bbr.2008.09.027] [Citation(s) in RCA: 314] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Revised: 09/16/2008] [Accepted: 09/18/2008] [Indexed: 11/22/2022]
Abstract
In this review we discuss the evidence that drug addiction, defined as a maladaptive compulsive habit, results from the progressive subversion by addictive drugs of striatum-dependent operant and Pavlovian learning mechanisms that are usually involved in the control over behaviour by stimuli associated with natural reinforcement. Although mainly organized through segregated parallel cortico-striato-pallido-thalamo-cortical loops involved in motor or emotional functions, the basal ganglia, and especially the striatum, are key mediators of the modulation of behavioural responses, under the control of both action-outcome and stimulus-response mechanisms, by incentive motivational processes and Pavlovian associations. Here we suggest that protracted exposure to addictive drugs recruits serial and dopamine-dependent, striato-nigro-striatal ascending spirals from the nucleus accumbens to more dorsal regions of the striatum that underlie a shift from action-outcome to stimulus-response mechanisms in the control over drug seeking. When this progressive ventral to dorsal striatum shift is combined with drug-associated Pavlovian influences from limbic structures such as the amygdala and the orbitofrontal cortex, drug seeking behaviour becomes established as an incentive habit. This instantiation of implicit sub-cortical processing of drug-associated stimuli and instrumental responding might be a key mechanism underlying the development of compulsive drug seeking and the high vulnerability to relapse which are hallmarks of drug addiction.
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Touzani K, Bodnar R, Sclafani A. Activation of dopamine D1-like receptors in nucleus accumbens is critical for the acquisition, but not the expression, of nutrient-conditioned flavor preferences in rats. Eur J Neurosci 2008; 27:1525-33. [PMID: 18336564 DOI: 10.1111/j.1460-9568.2008.06127.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study investigated the role of dopamine neurotransmission within the nucleus accumbens (NAc) in flavor preference learning induced by the postoral consequences of carbohydrates. In Experiment 1, rats fitted with a gastric catheter were trained with a flavor (CS+) paired with intragastric (IG) infusions of 8% glucose and a different flavor (CS-) paired with IG water infusions. The CS+ preference was then evaluated in two-bottle preference tests following bilateral injection of the dopamine D1-like receptor antagonist SCH23390 into the NAc shell at total doses of 0, 12, 24 and 48 nmol. SCH23390 produced dose-related reductions in CS+ intake but did not block the CS+ preference except at the highest dose, which also greatly suppressed the CS intakes. In Experiment 2, new rats were injected daily in the NAc shell with either saline or SCH23390 (12 nmol), 10 min prior to training sessions with CS+ with IG glucose and CS- with IG water. In the two-bottle preference tests, the drug-treated rats, unlike the control rats, did not significantly prefer the CS+ (61 vs. 83% preference). In Experiment 3, new rats were trained with the same procedures as Experiment 2, except that brain injections were in the NAc core. In contrast to control rats, SCH-treated rats failed to prefer the CS+ to the CS- in two-bottle tests (55% vs. 89% preference). These results demonstrate that D1-like receptors in the NAc shell and core are greatly involved in the acquisition, but less so in the expression, of a flavor preference conditioned by postingestive effects of glucose.
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Affiliation(s)
- Khalid Touzani
- Cognition, Brain and Behaviour Doctoral Subprogram, Department of Psychology, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA.
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Gourley SL, Wu FJ, Kiraly DD, Ploski JE, Kedves AT, Duman RS, Taylor JR. Regionally specific regulation of ERK MAP kinase in a model of antidepressant-sensitive chronic depression. Biol Psychiatry 2008; 63:353-9. [PMID: 17889834 PMCID: PMC2277331 DOI: 10.1016/j.biopsych.2007.07.016] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 07/23/2007] [Accepted: 07/24/2007] [Indexed: 11/20/2022]
Abstract
BACKGROUND Elevated phosphorylation of neurotrophin-regulated transcription factors, such as cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB), in the hippocampus has been proposed as a common mediator of antidepressant (ADT) efficacy in otherwise naive rodents. The intracellular factors by which ADTs and glucocorticoids, causal factors in depression, regulate depression-like behavior remain unclear, but extracellular signal-regulated kinase 1/2 (ERK1/2), upstream of CREB, is a likely candidate. METHODS We explored the long-term consequences of glucocorticoid exposure and subsequent ADT treatment in a novel model of chronic depression. Motivated behaviors, immobility during tail suspension, and ERK1/2, known to be required for behavioral response to ADTs, were quantified. RESULTS Chronic corticosterone (CORT) increased immobility, decreased responding in an operant conditioning task of motivation, and selectively reduced phosphorylated ERK1/2 (pERK1/2) in the dentate gyrus. Behavioral and biochemical measures were restored to baseline by amitriptyline (AMI) treatment. Corticosterone regulated pERK1/2 on a time course that paralleled increases in heat shock proteins associated with depression and decreased tyrosine kinase receptor B (trkB) phosphorylation. Chronic AMI also produced regionally dissociable effects on pERK1/2 in CA1/CA3, amygdala, and striatum, but not prefrontal cortex. CONCLUSIONS Antidepressant efficacy in a motivational task and behavioral despair assay are associated with altered limbic pERK1/2, including restored pERK1/2 in the dentate gyrus after stress-related insult.
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Affiliation(s)
- Shannon L. Gourley
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University, New Haven, CT
| | - Florence J. Wu
- Department of Psychology, Yale University, New Haven, CT
| | - Drew D. Kiraly
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University, New Haven, CT
| | | | - Alexia T. Kedves
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University, New Haven, CT
| | - Ronald S. Duman
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University, New Haven, CT
- Department of Pharmacology, Yale University, New Haven, CT
| | - Jane R. Taylor
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University, New Haven, CT
- Department of Psychology, Yale University, New Haven, CT
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Opposing regulation of pair bond formation by cAMP signaling within the nucleus accumbens shell. J Neurosci 2008; 27:13352-6. [PMID: 18045929 DOI: 10.1523/jneurosci.3216-07.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The formation of monogamous pair bonds, by prairie voles, is facilitated by activation of dopamine (DA) D2-like, but not D1-like, receptors within the nucleus accumbens (NAcc) shell. Because DA exerts opposing regulation of cAMP production depending on the subtype of receptor activated, we tested the hypothesis that DA regulation of pair bond formation is mediated via the cAMP signaling cascade. Consistent with activation of D2-like receptors, decreasing cAMP signaling, by blocking cAMP binding sites on protein kinase A (PKA), facilitated partner preference formation. Conversely, increasing cAMP signaling, by preventing the activation of inhibitory G-proteins, activating stimulatory G-proteins, or stimulating PKA prevented the formation of mating-induced partner preferences. These manipulations were effective in the shell, but not the core, of the NAcc. Together, these data demonstrate opposing regulation over pair bond formation by cAMP signaling within the NAcc shell.
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Warrier A, Hjelmstad GO. Protein kinase inhibitors reduce GABA but not glutamate release in the nucleus accumbens. Neuropharmacology 2007; 53:925-9. [PMID: 17961609 DOI: 10.1016/j.neuropharm.2007.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 09/07/2007] [Accepted: 09/07/2007] [Indexed: 10/22/2022]
Abstract
We investigated the role of endogenous protein kinase activity on synaptic transmission in the rat nucleus accumbens slice. The isoquinolinesulfonamide H-7 (50muM), a non-selective serine/threonine protein kinase inhibitor, had no effect on pharmacologically isolated glutamatergic EPSCs. However, it reduced GABA release in a dose-dependent manner. This effect of H-7 was not mimicked by the selective cAMP-dependent protein kinase inhibitor H-89, the PKC inhibitor Bisindolylmaleimide-1, or the cGMP-dependent protein kinase inhibitor KT5823. However, bath application of the myosin light chain kinase (MLCK) inhibitor, ML-7, significantly reduced IPSC amplitudes and partially occluded the reduction in IPSCs observed following bath application of H-7. These results suggest that endogenous protein kinase activity, specifically MLCK activity, regulates GABA, but not glutamate release, onto medium spiny neurons in the nucleus accumbens.
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Affiliation(s)
- Ajithkumar Warrier
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, CA 94608, USA
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Baiardi G, Ruiz AM, Beling A, Borgonovo J, Martínez G, Landa AI, Sosa MA, Gargiulo PA. Glutamatergic ionotropic blockade within accumbens disrupts working memory and might alter the endocytic machinery in rat accumbens and prefrontal cortex. J Neural Transm (Vienna) 2007; 114:1519-28. [PMID: 17616844 DOI: 10.1007/s00702-007-0776-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 06/10/2007] [Indexed: 11/27/2022]
Abstract
Effects of blocking N-methyl-D-aspartic acid (NMDA) and non-NMDA glutamatergic receptors on performance in the hole board test was studied in male rats bilaterally cannulated into the nucleus accumbens (Acc). Rats, divided into 5 groups, received either 1 microl injections of saline, (+/-) 2-amino-7-phosphonoheptanoic acid (AP-7) (0.5 or 1 microg) or 2,3-dioxo-6-nitro-1,2,3,4,tetrahydrobenzo-(f)quinoxaline-7-sulphonamide disodium (NBQX, 0.5 or 1 microg) 10 min before testing. An increase by AP-7 was observed in ambulatory movements (0.5 microg; p < 0.05), non-ambulatory movements and number of movements (1 microg; p < 0.05); sniffing and total exploration (1 microg; p < 0.01). When holes were considered in order from the first to the fifth by the number of explorations, the most visited holes (first and second) of the AP-7 group were significantly higher than the corresponding holes of saline group (p < 0.05 for 0.5 microg and p < 0.001 for 1 microg). When the second hole was compared with the first of his group, a difference was only observed in the AP-7 1 microg group (p < 0.001). Increasing differences between the other holes and the first were observed by drug treatment. At molecular level, it was observed that AP-7 induced an increase of the coat protein AP-2 expression in Acc, but not AP-180 neither the synaptic protein synaptophysin. The increase of AP-2 was also observed in the medial prefrontal cortex by the action of AP-7 but not NBQX. We conclude that NMDA glutamatergic blockade might induce an activation of the endocytic machinery into the Acc, leading to stereotypies and perseverations, lacking cortical intentional direction.
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Affiliation(s)
- G Baiardi
- Laboratorio de Neurociencias y Psicología Experimental, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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Berridge KC. The debate over dopamine's role in reward: the case for incentive salience. Psychopharmacology (Berl) 2007; 191:391-431. [PMID: 17072591 DOI: 10.1007/s00213-006-0578-x] [Citation(s) in RCA: 1419] [Impact Index Per Article: 83.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 08/20/2006] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Debate continues over the precise causal contribution made by mesolimbic dopamine systems to reward. There are three competing explanatory categories: 'liking', learning, and 'wanting'. Does dopamine mostly mediate the hedonic impact of reward ('liking')? Does it instead mediate learned predictions of future reward, prediction error teaching signals and stamp in associative links (learning)? Or does dopamine motivate the pursuit of rewards by attributing incentive salience to reward-related stimuli ('wanting')? Each hypothesis is evaluated here, and it is suggested that the incentive salience or 'wanting' hypothesis of dopamine function may be consistent with more evidence than either learning or 'liking'. In brief, recent evidence indicates that dopamine is neither necessary nor sufficient to mediate changes in hedonic 'liking' for sensory pleasures. Other recent evidence indicates that dopamine is not needed for new learning, and not sufficient to directly mediate learning by causing teaching or prediction signals. By contrast, growing evidence indicates that dopamine does contribute causally to incentive salience. Dopamine appears necessary for normal 'wanting', and dopamine activation can be sufficient to enhance cue-triggered incentive salience. Drugs of abuse that promote dopamine signals short circuit and sensitize dynamic mesolimbic mechanisms that evolved to attribute incentive salience to rewards. Such drugs interact with incentive salience integrations of Pavlovian associative information with physiological state signals. That interaction sets the stage to cause compulsive 'wanting' in addiction, but also provides opportunities for experiments to disentangle 'wanting', 'liking', and learning hypotheses. Results from studies that exploited those opportunities are described here. CONCLUSION In short, dopamine's contribution appears to be chiefly to cause 'wanting' for hedonic rewards, more than 'liking' or learning for those rewards.
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Affiliation(s)
- Kent C Berridge
- Department of Psychology, University of Michigan, 530 Church Street (East Hall), Ann Arbor, MI 48109, USA.
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Gerdjikov TV, Giles AC, Swain SN, Beninger RJ. Nucleus accumbens PKA inhibition blocks acquisition but enhances expression of amphetamine-produced conditioned activity in rats. Psychopharmacology (Berl) 2007; 190:65-72. [PMID: 17047929 DOI: 10.1007/s00213-006-0590-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 09/11/2006] [Indexed: 11/25/2022]
Abstract
RATIONALE The nucleus accumbens (NAc) plays a central role in dopamine-produced reward-related learning. In previous studies, the cyclic adenosine monophosphate-dependent protein kinase (PKA) inhibitor Rp-Cyclic 3',5'-hydrogen phosphorothioate adenosine triethylammonium salt (Rp-cAMPS) blocked the acquisition but not expression of NAc reward-related learning for natural rewards and the acquisition of psychostimulant drug conditioning. OBJECTIVES The current study assessed the role of PKA in the expression of NAc amphetamine (amph)-produced conditioning using conditioned activity (CA). MATERIALS AND METHODS After 5 days of habituation, a test environment was paired with bilateral NAc injections of amph (0.0 or 25.0 micro g) and the PKA inhibitor Rp-cAMPS (0.0, 5.0, 10.0, or 20.0 micro g) over three 60-min conditioning sessions separated by 48 h. To test for effects on expression, some groups received vehicle or amph alone before conditioning sessions and were injected with 0.0, 0.25, 5.0, or 20.0 mug of Rp-cAMPS before the single 60-min test session. RESULTS Amph produced acute increases in locomotion and robust CA. Rp-cAMPS impaired the acquisition of amph-produced CA but not its expression; in fact, it enhanced expression. CONCLUSIONS Results show that PKA inhibition blocks the acquisition but not the expression of amph-produced conditioning.
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El-Ghundi M, O'Dowd BF, George SR. Insights into the Role of Dopamine Receptor Systems in Learning and Memory. Rev Neurosci 2007; 18:37-66. [PMID: 17405450 DOI: 10.1515/revneuro.2007.18.1.37] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is well established that learning and memory are complex processes involving and recruiting different brain modulatory neurotransmitter systems. Considerable evidence points to the involvement of dopamine in various aspects of cognition, and interest has been focused on investigating the clinical relevance of dopamine systems to age-related cognitive decline and manifestations of cognitive impairment in schizophrenia, Alzheimer's disease, Parkinson's disease and other neurodegenerative diseases. In the past decade or so, in spite of the molecular cloning of the five dopamine receptor subtypes, their specific roles in brain function remained inconclusive due to the lack of completely selective ligands that could distinguish between the members of the D1-like and D2-like dopamine receptor families. One of the most important advances in the field of dopamine research has been the generation of mutant mouse models permitting evaluation of the dopaminergic system using gene targeting technologies. These mouse models represent an important approach to explore the functional roles of closely related receptor subtypes. In this review, we present and discuss evidence on the role of dopamine receptors in different aspects of learning and memory at the cellular, molecular and behavioral levels. We compare evidence using conventional pharmacological, lesion or electrophysiological studies with results from mice with targeted deletions of different subtypes of dopamine receptor genes. We particularly focus on dopamine D1 and D2 receptors in an effort to delineate their specific roles in various aspects of cognitive function. We provide strong evidence, from our own recent work as well as others, that dopamine is part of the network that plays a very important role in cognitive function, and that although multiple dopamine receptor subtypes contribute to different aspects of learning and memory, the D1 receptor seems to play a more prominent role in mediating plasticity and specific aspects of cognitive function, including spatial learning and memory processes, reversal learning, extinction learning, and incentive learning.
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Affiliation(s)
- Mufida El-Ghundi
- Department of Pharmacology, University of Toronto, Ontario, Canada
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Xu X, Scott-Scheiern T, Kempker L, Simons K. Active avoidance conditioning in zebrafish (Danio rerio). Neurobiol Learn Mem 2007; 87:72-7. [PMID: 16861014 DOI: 10.1016/j.nlm.2006.06.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Revised: 06/14/2006] [Accepted: 06/14/2006] [Indexed: 11/25/2022]
Abstract
The zebrafish represents a potentially useful organism for studying genes involved in learning and memory function in vertebrates, because a number of genetic techniques in zebrafish have been developed to produce a wide variety of genetic mutants. While zebrafish mutants are being developed, behavioral studies on learning and memory function in zebrafish are in urgent need. The present study investigated active avoidance conditioning in normal zebrafish. Zebrafish were trained to swim from a lighted (CS) compartment to a dark compartment to avoid an electrical body shock (US) in a shuttle-box that consisted of a water-filled tank separated by an opaque barrier into two equal compartments. By varying the number of trials per training session and the duration of the intertrial interval, Experiments 1 and 2 showed that, with the CS, US, and intertrial interval being 12s, zebrafish learned avoidance responses within a training session consisting of 30 trials and retained the avoidance responses. Experiment 3 showed that zebrafish learned avoidance responses following the association between the CS of light and the US of shock in the avoidance conditioning paradigm. Using the avoidance conditioning paradigm, Experiment 4 investigated the amnestic effects of N-methyl-D-aspartate receptor antagonist MK-801 and nitric oxide synthase inhibitor L-NAME in zebrafish. Experiment 4 showed that post-training injection of L-NAME significantly impaired retention of avoidance responses while MK-801 did not, confirming previous results with other vertebrates. The results of the present study suggest the similar involvements of neurochemicals in learning and memory among vertebrates. Thus, future studies with zebrafish mutants may identify genes involved in learning and memory in vertebrates.
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Affiliation(s)
- Xiaojuan Xu
- Department of Psychology, Grand Valley State University, Allendale, MI 49401, USA.
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40
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Haile CN, Kosten TR, Kosten TA. Genetics of dopamine and its contribution to cocaine addiction. Behav Genet 2006; 37:119-45. [PMID: 17063402 DOI: 10.1007/s10519-006-9115-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Accepted: 09/07/2006] [Indexed: 12/30/2022]
Abstract
Cocaine addiction is a major health and social problem for which there are presently no effective pharmacotherapies. Many of the most promising medications target dopamine based on the large literature that supports its role in addiction. Recent studies show that genetic factors are also important. Rodent models and gene knock-out technology have helped elucidate the involvement of specific genes in the function of the dopamine reward system and intracellular cascades that lead to neuronal changes in this system. Human epidemiological, linkage, and association studies have identified allelic variants (polymorphisms) that give rise to altered metabolism of dopamine and its functional consequences. Individuals with these polymorphisms respond differently to psychostimulants and possibly to pharmacotherapies. Here we review the literature on genetic variations that affect dopamine neurotransmission, responses to psychostimulants and potential treatments for cocaine addiction. Behavioral responses to psychostimulants in animals with different or modified genetics in dopamine signaling are discussed. We also review polymorphisms in humans that affect dopaminergic neurotransmission and alter the subjective effects of psychostimulants. Pharmacotherapies may have increased efficacy when targeted to individuals possessing specific genetic polymophisms in dopamine's metabolic and intracellular messenger systems.
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Affiliation(s)
- Colin N Haile
- Michael E. DeBakey VA Medical Center, and Meninger Department of Psychiatry, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Olausson P, Jentsch JD, Tronson N, Neve RL, Nestler EJ, Taylor JR. DeltaFosB in the nucleus accumbens regulates food-reinforced instrumental behavior and motivation. J Neurosci 2006; 26:9196-204. [PMID: 16957076 PMCID: PMC6674495 DOI: 10.1523/jneurosci.1124-06.2006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 06/23/2006] [Accepted: 08/02/2006] [Indexed: 11/21/2022] Open
Abstract
Alterations in motivation have been implicated in the pathophysiology of several psychiatric disorders, including substance abuse and depression. Repeated exposure to drugs of abuse or stress is known to persistently induce the transcription factor deltaFosB in the nucleus accumbens (NAc) and dorsal striatum, effects hypothesized to contribute to neuroadaptations in dopamine-regulated signaling. Little is known, however, about the specific involvement of deltaFosB in dysregulation of appetitively motivated behaviors. We show here that inducible overexpression of deltaFosB in NAc and dorsal striatum of bitransgenic mice, or specifically in the NAc core of rats by use of viral-mediated gene transfer, enhanced food-reinforced instrumental performance and progressive ratio responding. Very similar behavioral effects were found after previous repeated exposure to cocaine, amphetamine, MDMA [(+)-3,4-methylenedioxymethamphetamine], or nicotine in rats. These results reveal the powerful regulation of motivational processes by deltaFosB, and provide evidence that drug-induced alterations in gene expression via induction of deltaFosB within the NAc core may play a critical role in the impact of motivational influences on instrumental behavior.
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Affiliation(s)
- Peter Olausson
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
| | - J. David Jentsch
- Department of Psychology, University of California, Los Angeles, California 90095
| | - Natalie Tronson
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
| | - Rachel L. Neve
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts 02178, and
| | - Eric J. Nestler
- Department of Psychiatry and Center for Basic Neuroscience, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Jane R. Taylor
- Department of Psychiatry, Division of Molecular Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
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Abstract
The ability of food to establish and maintain response habits and conditioned preferences depends largely on the function of brain dopamine systems. While dopaminergic transmission in the nucleus accumbens appears sufficient for some forms of reward, the role of dopamine in food reward does not appear to be restricted to this region. Dopamine plays an important role in both the ability to energize feeding and to reinforce food-seeking behaviour; the role in energizing feeding is secondary to the prerequisite role in reinforcement. Dopaminergic activation is triggered by the auditory and visual as well as the tactile, olfactory, and gustatory stimuli of foods. While dopamine plays a central role in the feeding and food-seeking of normal animals, some food rewarded learning can be seen in genetically engineered dopamine-deficient mice.
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Affiliation(s)
- Roy A Wise
- Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, Baltimore, MD 21224, USA.
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43
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Will MJ, Pratt WE, Kelley AE. Pharmacological characterization of high-fat feeding induced by opioid stimulation of the ventral striatum. Physiol Behav 2006; 89:226-34. [PMID: 16854442 DOI: 10.1016/j.physbeh.2006.06.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 05/20/2006] [Accepted: 06/08/2006] [Indexed: 11/28/2022]
Abstract
Nucleus accumbens mu-opioid stimulation causes marked increases in the intake of highly palatable foods, such as a high-fat diet. However, to date there has been little examination of how other striatal neurotransmitters may mediate opioid-driven feeding of palatable foodstuffs. In the current study, free feeding rats with bilateral cannulae aimed at the nucleus accumbens received intra-accumbens pretreatment with antagonists for dopamine D-1 (SCH23390; 0 microg or 1 microg/0.5 microl/side), dopamine D-2 (raclopride; 0 microg or 2.0 microg/0.5 microl/side), AMPA (LY293558; 0 microg, 0.01 microg or 0.10 microg/0.5 microl/side), muscarinic (scopolamine 0 microg, 0.1, 1.0, or 10 microg/0.5 microl/side) or nicotinic (mecamylamine; 0 microg, 10 microg/0.5 microl/side) receptors, immediately prior to infusions of the mu-receptor agonist D-Ala2, NMe-Phe4, Glyol5-enkephalin (DAMGO; 0.25 microg/0.5 microl) or vehicle. The effects of these pretreatments on 2 hr fat intake was compared to pretreatment with a general opioid antagonist (naltrexone; 0 microg or 20 microg/0.5 microl/side). DAMGO-induced feeding was unaffected by prior antagonism of dopamine, glutamate, or nicotinic receptors. As expected, naltrexone infusions blocked DAMGO-elicited fat intake. Antagonism of muscarinic acetylcholine receptors reduced feeding in both the DAMGO and vehicle-treated conditions. In an additional experiment, cholinergic receptor stimulation alone did not affect intake of the fat diet, suggesting that nucleus accumbens cholinergic stimulation is insufficient to alter feeding of a highly palatable food. These data suggest that the feeding effects caused by striatal opioid stimulation are independent from or downstream to the actions of dopamine and glutamate signaling, and provide novel insight into the role of striatal acetylcholine on feeding behaviors.
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MESH Headings
- Analysis of Variance
- Animals
- Appetite Regulation/drug effects
- Appetite Regulation/physiology
- Dietary Fats
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/administration & dosage
- Feeding Behavior/drug effects
- Feeding Behavior/physiology
- Male
- Microinjections
- Neurotransmitter Agents/administration & dosage
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, Cholinergic/drug effects
- Receptors, Cholinergic/physiology
- Receptors, Dopamine/drug effects
- Receptors, Dopamine/physiology
- Receptors, Glutamate/drug effects
- Receptors, Glutamate/physiology
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Taste/drug effects
- Taste/physiology
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Affiliation(s)
- Matthew J Will
- Department of Psychological Sciences, University of Missouri, Columbia, Christopher Bond Life Sciences Center, 1201 Rollins St., Columbia, MO 65211, United States
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Barker GRI, Bashir ZI, Brown MW, Warburton EC. A temporally distinct role for group I and group II metabotropic glutamate receptors in object recognition memory. Learn Mem 2006; 13:178-86. [PMID: 16585793 PMCID: PMC1409835 DOI: 10.1101/lm.77806] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recognition memory, involving the ability to discriminate between a novel and familiar object, depends on the integrity of the perirhinal cortex (PRH). Glutamate, the main excitatory neurotransmitter in the cortex, is essential for many types of memory processes. Of the subtypes of glutamate receptor, metabotropic receptors (mGluRs) have received less study than NMDA receptors; thus, the reported experiments examined the role of mGluRs in familiarity discrimination in the rat PRH. Experiments 1 and 2 assessed the effects of systemic administration of MPEP, a group I mGluR (specifically mGluR5) antagonist, and/or LY341495, a group II mGluR antagonist, on a spontaneous object novelty preference task. Simultaneous antagonism of both group I and II mGluRs impaired familiarity discrimination following a 24-h but not a 15-min delay, while antagonism of either mGluR subtype alone had no effect at either delay. The impairment was in acquisition, as in Experiment 3 coadministration of MPEP and LY341495 did not affect recognition memory performance when administered either after the sample phase or prior to test. The impairment in long-term recognition memory was mediated by mGluRs in the PRH, as localized intracortical antagonism of group I and II mGluRs also produced a deficit (Experiment 4). No evidence was found for an involvement of group III mGluRs in the acquisition of long-term familiarity discrimination (Experiment 5). These findings establish that glutamatergic neurotransmission in the PRH via group I and II mGluRs is crucial for the acquisition, but not for the consolidation or retrieval of long-term object recognition memory.
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Affiliation(s)
- Gareth Robert Isaac Barker
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1 TD, United Kingdom
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45
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Gerdjikov TV, Beninger RJ. Place preference induced by nucleus accumbens amphetamine is impaired by local blockade of Group II metabotropic glutamate receptors in rats. BMC Neurosci 2006; 7:43. [PMID: 16734896 PMCID: PMC1501036 DOI: 10.1186/1471-2202-7-43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2006] [Accepted: 05/30/2006] [Indexed: 11/10/2022] Open
Abstract
Background The nucleus accumbens (NAc) plays a critical role in amphetamine-produced conditioned place preference (CPP). In previous studies, NAc basal and amphetamine-produced DA transmission was altered by Group II mGluR agents. We tested whether NAc amphetamine CPP depends on Group II mGluR transmission. Results NAc injections (0.5 μl/side) of the Group II mGluR antagonist (2 S)- a-ethylglutamic acid (EGLU: 0.01–0.8 μg but not 0.001 μg) impaired CPP. The drug did not block the acute locomotor effect of amphetamine. Conclusion Results suggest that Group II mGluRs may be necessary for the establishment of NAc amphetamine-produced CPP. These receptors may also mediate other forms of reward-related learning dependent on this structure.
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Affiliation(s)
- Todor V Gerdjikov
- Department of Psychology, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Richard J Beninger
- Department of Psychology, Queen's University, Kingston, ON K7L 3N6, Canada
- Department of Psychiatry, Queen's University, Kingston, ON K7L 3N6, Canada
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Cheng J, Feenstra MGP. Individual differences in dopamine efflux in nucleus accumbens shell and core during instrumental learning. Learn Mem 2006; 13:168-77. [PMID: 16585792 PMCID: PMC1409831 DOI: 10.1101/lm.1806] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Accepted: 01/02/2006] [Indexed: 01/23/2023]
Abstract
Combined activation of dopamine D1- and NMDA-glutamate receptors in the nucleus accumbens has been strongly implicated in instrumental learning, the process in which an individual learns that a specific action has a wanted outcome. To assess dopaminergic activity, we presented rats with two sessions (30 trials each) of a one-lever appetitive instrumental task and simultaneously measured dopamine efflux in the shell and core accumbens subareas using in vivo microdialysis. Dopamine efflux was increased during each session in all areas. The behavioral performance of the rats in the second session led us to divide them into a learning group (>90% correct trials) and a non-learning group. In the first session, the rats of the learning group showed significantly higher increases. The difference was most pronounced in the shell. In the second session, the dopamine increase was similar in both groups, although the learning groups now pressed the lever about three times more often and consequently obtained more rewards. We conclude that task-related activation of dopamine efflux is different between learning and non-learning rats only during the learning phase. These results support the pharmacological evidence that dopamine is of particular importance during the instrumental learning process.
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Affiliation(s)
- Jingjun Cheng
- Netherlands Institute for Brain Research, 1105 AZ Amsterdam, The Netherlands
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47
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Park H, Lee JA, Lee C, Kim MJ, Chang DJ, Kim H, Lee SH, Lee YS, Kaang BK. An Aplysia type 4 phosphodiesterase homolog localizes at the presynaptic terminals of Aplysia neuron and regulates synaptic facilitation. J Neurosci 2006; 25:9037-45. [PMID: 16192395 PMCID: PMC6725601 DOI: 10.1523/jneurosci.1989-05.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The cAMP-dependent signaling pathway is critically involved in memory-related synaptic plasticity. cAMP-specific type 4 phosphodiesterases (PDE4) play a role in this process by regulating the cAMP concentration. However, it is unclear how PDE4 is involved in regulating synaptic plasticity. To address this issue in Aplysia sensory-to-motor synapses, we identified a long isoform of the PDE4 homolog in Aplysia kurodai (apPDE), with genetic and biochemical properties similar to those of mammalian PDE4s. Furthermore, apPDE is localized to the membrane and presynaptic region. Both apPDE overexpression and knock-down impaired short- and long-term facilitation, indicating that an appropriate expression level of apPDE in synaptic regions is required for normal synaptic facilitation. By using fluorescence resonance energy transfer-based measurement of in vivo protein kinase A (PKA) activation, we found that the PKA activation by 5-hydroxytryptamine (5-HT) was impaired in both apPDE-overexpressed and knock-down synapses. Analogous to the inhibition of apPDE by RNA interference, chronic rolipram treatment before 5-HT stimulation also impaired the PKA activation by 5-HT, suggesting that regulation of the synaptic cAMP level by PDE4 is critical for normal synaptic facilitation. Together, we suggest that PDE4s localized in the synapses play a critical role in regulating the optimum cAMP level required for normal synaptic plasticity.
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Affiliation(s)
- Hyungju Park
- National Research Laboratory of Neurobiology, Institute of Molecular Biology and Genetics, School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Korea
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Lynch WJ, Taylor JR. Persistent changes in motivation to self-administer cocaine following modulation of cyclic AMP-dependent protein kinase A (PKA) activity in the nucleus accumbens. Eur J Neurosci 2006; 22:1214-20. [PMID: 16176364 DOI: 10.1111/j.1460-9568.2005.04305.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Drug-induced neuroadaptations within the nucleus accumbens, including activation of cAMP-dependent protein kinase A (PKA), may contribute to the synaptic plasticity and behavioural changes that underlie drug addiction. As a direct test of this hypothesis, we examined the effects in rats of PKA activation (Sp-cAMPS infusions of 10 and 20 nmol/side) and inhibition (Rp-cAMPS infusions of 10 and 20 nmol/side) in the nucleus accumbens on motivation to obtain cocaine as measured by responding under the progressive-ratio schedule. Bilateral infusions of Sp-cAMPS (20 nmol/side) resulted in an increase in progressive-ratio responding for cocaine and this effect persisted for several days. In contrast, Rp-cAMPS (20 nmol/side) produced persistent decreases in progressive-ratio responding for cocaine beginning on the day of administration and lasting for several days. These data suggest that alternations in PKA activity within the nucleus accumbens as a consequence of repeated cocaine exposure may contribute to addiction by producing persistent increases in motivation to obtain cocaine.
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Affiliation(s)
- W J Lynch
- Department of Psychiatry, Yale University School of Medicine, CMHC, Abraham Ribicoff Research Facilities, 34 Park Street, New Haven, CT 06508, USA.
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Hara Y, Pickel VM. Overlapping intracellular and differential synaptic distributions of dopamine D1 and glutamate N-methyl-D-aspartate receptors in rat nucleus accumbens. J Comp Neurol 2005; 492:442-55. [PMID: 16228995 PMCID: PMC2605084 DOI: 10.1002/cne.20740] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The dopamine D1 receptor (D1R) in the nucleus accumbens (Acb) shell is highly implicated in psychostimulant-evoked locomotor activity and reward, whereas the D1R in the Acb core is more crucial for appetitive instrumental learning. These behavioral effects depend in part on interactions involving glutamatergic N-methyl-D-aspartate (NMDA) receptors, whose essential NR1 subunit has physical associations with the D1R. To determine the relevant sites for D1R activation and interactions involving NMDA receptors, we examined the electron microscopic immunolabeling of D1R and NR1 C-terminal peptides in rat Acb shell and core. In each Acb subdivision, the D1Rs were located principally on extrasynaptic plasma membranes of dendritic shafts and spines and more rarely were associated with cytoplasmic endomembranes. Many D1R-labeled somata and dendrites also contained NR1 immunoreactivity. In comparison with D1R, NR1 immunoreactivity was more often seen in the cytoplasm and near asymmetric synapses on somatodendritic profiles. In these profiles, notable overlapping distributions of D1R and NR1 occurred near endomembranes. The exclusively D1R- or D1R- and NR1-containing dendrites were most prevalent in the Acb shell, but were also present in the Acb core. In each region, NR1 was also detected in axon terminals without D1R, which formed excitatory-type synapses with D1R-labeled dendrites. These results provide ultrastructural evidence that D1Rs in the Acb have subcellular distributions supporting, 1) intracellular cotrafficking with NR1 and 2) modulation of the postsynaptic excitability in spiny neurons affected by presynaptic NMDA receptor activation. The region-specific differences in receptor distributions suggest a major, but not exclusive, involvement of Acb D1R in reward-related processing.
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Affiliation(s)
- Yuko Hara
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA
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Gargiulo PA, Acerbo MJ, Krug I, Delius JD. Cognitive effects of dopaminergic and glutamatergic blockade in nucleus accumbens in pigeons. Pharmacol Biochem Behav 2005; 81:732-9. [PMID: 15979133 DOI: 10.1016/j.pbb.2005.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 05/19/2005] [Accepted: 05/20/2005] [Indexed: 10/25/2022]
Abstract
In earlier studies it was found that glutamatergic transmission within the nucleus accumbens septi is involved in the performance of a learned visual shape discrimination in pigeons. This study examines what effects several kinds of glutamate and dopamine antagonists have on the same task. Pigeons were trained with the relevant discrimination, bilaterally implanted with cannulas into the nucleus accumbens and tested after various transmission blockers had been administered intracerebrally. SCH-23390, a D1 dopamine antagonist, at the dose used, had no effect, and Spiperone, a D2-dopamine and 5HT2a-serotonine antagonist, significantly decreased the error repeat trials. CNQX, a non-NMDA glutamate receptor antagonist, and Cycloleucine, an antagonist of the glycine allosteric site of NMDA receptors, had no effect. CGS-19755, a selective competitive NMDA antagonist, significantly impaired performance by significantly decreasing the percent correct trials and increasing the error repeat trials. CPPG, a II/III metabotropic glutamate antagonist, remarkably improved performance. MMPG, a III/II metabotropic glutamate antagonist, at the dose used, did not have any significant effect. The preparation employed may be a useful animal model of perceptual disturbances in schizophrenia.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Alanine/analogs & derivatives
- Alanine/pharmacology
- Animals
- Benzazepines/pharmacology
- Cognition/drug effects
- Columbidae
- Cycloleucine/pharmacology
- Discrimination Learning/drug effects
- Dopamine Antagonists/pharmacology
- Dopamine D2 Receptor Antagonists
- Excitatory Amino Acid Antagonists/pharmacology
- Glycine/analogs & derivatives
- Glycine/pharmacology
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/metabolism
- Pipecolic Acids/pharmacology
- Random Allocation
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/metabolism
- Receptors, Metabotropic Glutamate/antagonists & inhibitors
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/metabolism
- Serotonin 5-HT2 Receptor Antagonists
- Spiperone/pharmacology
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Affiliation(s)
- P A Gargiulo
- Laboratorio de Neurociencias y Psicología Experimental (IMBECU-CONICET), Dept. Patología, F.C.M., U. N. de Cuyo, y Universidad Católica Argentina, Mendoza (5500), Argentina.
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