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Nunes EJ, Kebede N, Bagdas D, Addy NA. Cholinergic and dopaminergic-mediated motivated behavior in healthy states and in substance use and mood disorders. J Exp Anal Behav 2022; 117:404-419. [PMID: 35286712 PMCID: PMC9743782 DOI: 10.1002/jeab.747] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 02/06/2023]
Abstract
Acetylcholine is an important neuromodulator of the mesolimbic dopamine (DA) system, which itself is a mediator of motivated behavior. Motivated behavior can be described by two primary components, termed directional and activational motivation, both of which can be examined and dissociated using effort-choice tasks. The directional component refers to motivated behavior directed towards reinforcing stimuli and away from aversive stimuli. Behaviors characterized by increased vigor, persistence, and work output are considered to reflect activational components of motivation. Disruption of DA signaling has been shown to decrease activational components of motivation, while leaving directional features intact. Facilitation of DA release promotes the activational aspects of motivated behavior. In this review, we discuss cholinergic and DA regulation of motivated behaviors. We place emphasis on effort-choice processes and the ability of effort-choice tasks to examine and dissociate changes of motivated behavior in the context of substance use and mood disorders. Furthermore, we consider how altered cholinergic transmission impacts motivated behavior across disease states, and the possible role of cholinergic dysregulation in the etiology of these illnesses. Finally, we suggest that treatments targeting cholinergic activity may be useful in ameliorating motivational disruptions associated with substance use and comorbid substance use and mood disorders.
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Affiliation(s)
- Eric J. Nunes
- Department of Psychiatry, Yale School of Medicine,Yale Tobacco Center of Regulatory Science, Yale School of Medicine
| | - Nardos Kebede
- Department of Psychiatry, Yale School of Medicine,Yale Tobacco Center of Regulatory Science, Yale School of Medicine
| | - Deniz Bagdas
- Department of Psychiatry, Yale School of Medicine,Yale Tobacco Center of Regulatory Science, Yale School of Medicine
| | - Nii A. Addy
- Department of Psychiatry, Yale School of Medicine,Yale Tobacco Center of Regulatory Science, Yale School of Medicine,Department of Cellular and Molecular Physiology, Yale School of Medicine,Interdepartmental Neuroscience Program, Yale University,Wu Tsai Institute, Yale University
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2
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Lovinger DM, Mateo Y, Johnson KA, Engi SA, Antonazzo M, Cheer JF. Local modulation by presynaptic receptors controls neuronal communication and behaviour. Nat Rev Neurosci 2022; 23:191-203. [PMID: 35228740 PMCID: PMC10709822 DOI: 10.1038/s41583-022-00561-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2022] [Indexed: 12/15/2022]
Abstract
Central nervous system neurons communicate via fast synaptic transmission mediated by ligand-gated ion channel (LGIC) receptors and slower neuromodulation mediated by G protein-coupled receptors (GPCRs). These receptors influence many neuronal functions, including presynaptic neurotransmitter release. Presynaptic LGIC and GPCR activation by locally released neurotransmitters influences neuronal communication in ways that modify effects of somatic action potentials. Although much is known about presynaptic receptors and their mechanisms of action, less is known about when and where these receptor actions alter release, especially in vivo. This Review focuses on emerging evidence for important local presynaptic receptor actions and ideas for future studies in this area.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
| | - Yolanda Mateo
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Kari A Johnson
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Sheila A Engi
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mario Antonazzo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
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3
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Hadizadeh H, Flores J, Nunes E, Mayerson T, Potenza MN, Angarita GA. Novel Pharmacological Agents for the Treatment of Cocaine Use Disorder. Curr Behav Neurosci Rep 2022. [DOI: 10.1007/s40473-022-00246-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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4
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Accumbens Cholinergic Interneurons Mediate Cue-Induced Nicotine Seeking and Associated Glutamatergic Plasticity. eNeuro 2021; 8:ENEURO.0276-20.2020. [PMID: 33239269 PMCID: PMC7890519 DOI: 10.1523/eneuro.0276-20.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/04/2020] [Accepted: 11/16/2020] [Indexed: 12/23/2022] Open
Abstract
Nicotine, the primary addictive substance in tobacco, is widely abused. Relapse to cues associated with nicotine results in increased glutamate release within nucleus accumbens core (NAcore), modifying synaptic plasticity of medium spiny neurons (MSNs), which contributes to reinstatement of nicotine seeking. However, the role of cholinergic interneurons (ChIs) within the NAcore in mediating these neurobehavioral processes is unknown. ChIs represent less than 1% of the accumbens neuronal population and are activated during drug seeking and reward-predicting events. Thus, we hypothesized that ChIs may play a significant role in mediating glutamatergic plasticity that underlies nicotine-seeking behavior. Using chemogenetics in transgenic rats expressing Cre under the control of the choline acetyltransferase (ChAT) promoter, ChIs were bidirectionally manipulated before cue-induced reinstatement. Following nicotine self-administration and extinction, ChIs were activated or inhibited before a cue reinstatement session. Following reinstatement, whole-cell electrophysiology from NAcore MSNs was used to assess changes in plasticity, measured via AMPA/NMDA (A/N) ratios. Chemogenetic inhibition of ChIs inhibited cued nicotine seeking and resulted in decreased A/N, relative to control animals, whereas activation of ChIs was unaltered, demonstrating that ChI inhibition may modulate plasticity underlying cue-induced nicotine seeking. These results demonstrate that ChI neurons play an important role in mediating cue-induced nicotine reinstatement and underlying synaptic plasticity within the NAcore.
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Zachry JE, Nolan SO, Brady LJ, Kelly SJ, Siciliano CA, Calipari ES. Sex differences in dopamine release regulation in the striatum. Neuropsychopharmacology 2021; 46:491-499. [PMID: 33318634 PMCID: PMC8027008 DOI: 10.1038/s41386-020-00915-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/03/2020] [Accepted: 11/09/2020] [Indexed: 01/05/2023]
Abstract
The mesolimbic dopamine system-which originates in the ventral tegmental area and projects to the striatum-has been shown to be involved in the expression of sex-specific behavior and is thought to be a critical mediator of many psychiatric diseases. While substantial work has focused on sex differences in the anatomy of dopamine neurons and relative dopamine levels between males and females, an important characteristic of dopamine release from axon terminals in the striatum is that it is rapidly modulated by local regulatory mechanisms independent of somatic activity. These processes can occur via homosynaptic mechanisms-such as presynaptic dopamine autoreceptors and dopamine transporters-as well as heterosynaptic mechanisms, such as retrograde signaling from postsynaptic cholinergic and GABAergic systems, among others. These regulators serve as potential targets for the expression of sex differences in dopamine regulation in both ovarian hormone-dependent and independent fashions. This review describes how sex differences in microcircuit regulatory mechanisms can alter dopamine dynamics between males and females. We then describe what is known about the hormonal mechanisms controlling/regulating these processes. Finally, we highlight the missing gaps in our knowledge of these systems in females. Together, a more comprehensive and mechanistic understanding of how sex differences in dopamine function manifest will be particularly important in developing evidence-based therapeutics that target this system and show efficacy in both sexes.
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Affiliation(s)
- Jennifer E. Zachry
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA
| | - Suzanne O. Nolan
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA
| | - Lillian J. Brady
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA
| | - Shannon J. Kelly
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA
| | - Cody A. Siciliano
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN 37232 USA
| | - Erin S. Calipari
- grid.152326.10000 0001 2264 7217Department of Pharmacology, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232 USA ,grid.152326.10000 0001 2264 7217Department of Psychiatry and Behavioral Sciences, Vanderbilt University, Nashville, TN 37232 USA
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O'Neal TJ, Nooney MN, Thien K, Ferguson SM. Chemogenetic modulation of accumbens direct or indirect pathways bidirectionally alters reinstatement of heroin-seeking in high- but not low-risk rats. Neuropsychopharmacology 2020; 45:1251-1262. [PMID: 31747681 PMCID: PMC7297977 DOI: 10.1038/s41386-019-0571-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/05/2019] [Accepted: 11/11/2019] [Indexed: 12/29/2022]
Abstract
Opioid addiction has been declared a public health emergency, with fatal overdoses following relapse reaching epidemic proportions and disease-associated costs continuing to escalate. Relapse is often triggered by re-exposure to drug-associated cues, and though the neural substrates responsible for relapse in vulnerable individuals remains ambiguous, the nucleus accumbens (NAc) has been shown to play a central role. NAc direct and indirect pathway medium spiny neurons (dMSNs and iMSNs) can have oppositional control over reward-seeking and associative learning and are critically involved in reinstatement of psychostimulant-seeking. However, whether these pathways similarly regulate reinstatement of opioid-seeking remains unknown, as is their role in modulating motivation to take opioids. Here, we describe a method for classifying addiction severity in outbred rats following intermittent-access heroin self-administration that identifies subgroups as addiction-vulnerable (high-risk) or addiction-resistant (low-risk). Using dual viral-mediated gene transfer of DREADDs, we show that transient inactivation of dMSNs or activation of iMSNs is capable of suppressing cue-induced reinstatement of heroin-seeking in high- but not low-risk rats. Surprisingly, however, the motivation to self-administer heroin was unchanged, indicating a divergence in the encoding of heroin-taking and heroin-seeking in rats. We further show that transient activation of dMSNs or inactivation of iMSNs exacerbates cue-induced reinstatement of heroin-seeking in high- but not low-risk rats, again with no effect on motivation. These findings demonstrate a critical role for dMSNs and iMSNs in encoding vulnerability to reinstatement of heroin-seeking and provide insight into the specific neurobiological changes that occur in vulnerable groups following heroin self-administration.
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Affiliation(s)
- Timothy J O'Neal
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, 98195, USA
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA, 98195, USA
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Marlaena N Nooney
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Katie Thien
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Susan M Ferguson
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, 98195, USA.
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA, 98195, USA.
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA.
- Alcohol and Drug Abuse Institute, University of Washington, Seattle, WA, 98195, USA.
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Cholinergic M4 receptors are involved in morphine-induced expression of behavioral sensitization by regulating dopamine function in the nucleus accumbens of rats. Behav Brain Res 2019; 360:128-133. [DOI: 10.1016/j.bbr.2018.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/03/2018] [Accepted: 12/04/2018] [Indexed: 12/28/2022]
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8
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Nucleus Accumbens Microcircuit Underlying D2-MSN-Driven Increase in Motivation. eNeuro 2018; 5:eN-NWR-0386-17. [PMID: 29780881 PMCID: PMC5957524 DOI: 10.1523/eneuro.0386-18.2018] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/23/2018] [Accepted: 02/28/2018] [Indexed: 01/11/2023] Open
Abstract
The nucleus accumbens (NAc) plays a central role in reinforcement and motivation. Around 95% of the NAc neurons are medium spiny neurons (MSNs), divided into those expressing dopamine receptor D1 (D1R) or dopamine receptor D2 (D2R). Optogenetic activation of D2-MSNs increased motivation, whereas inhibition of these neurons produced the opposite effect. Yet, it is still unclear how activation of D2-MSNs affects other local neurons/interneurons or input terminals and how this contributes for motivation enhancement. To answer this question, in this work we combined optogenetic modulation of D2-MSNs with in loco pharmacological delivery of specific neurotransmitter antagonists in rats. First, we showed that optogenetic activation of D2-MSNs increases motivation in a progressive ratio (PR) task. We demonstrated that this behavioral effect relies on cholinergic-dependent modulation of dopaminergic signalling of ventral tegmental area (VTA) terminals, which requires D1R and D2R signalling in the NAc. D2-MSN optogenetic activation decreased ventral pallidum (VP) activity, reducing the inhibitory tone to VTA, leading to increased dopaminergic activity. Importantly, optogenetic activation of D2-MSN terminals in the VP was sufficient to recapitulate the motivation enhancement. In summary, our data suggests that optogenetic stimulation of NAc D2-MSNs indirectly modulates VTA dopaminergic activity, contributing for increased motivation. Moreover, both types of dopamine receptors signalling in the NAc are required in order to produce the positive behavioral effects.
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Liu X, Tian L, Cui R, Ruan H, Li X. Muscarinic receptors in the nucleus accumbens shell play different roles in context-induced or morphine-challenged expression of behavioral sensitization in rats. Eur J Pharmacol 2018; 819:51-57. [PMID: 29196177 DOI: 10.1016/j.ejphar.2017.11.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/17/2017] [Accepted: 11/24/2017] [Indexed: 01/01/2023]
Abstract
Both drug-related cues and drug priming are the main factors that induce relapse of drug addiction. Previous research has reported that blockade of the muscarinic receptors could significantly depress addictive behavior, suggesting that the muscarinic receptors might be involved in drug use and relapse behavior. The nucleus accumbens (NAc), especially the shell of the NAc, where the muscarinic receptors are expressed, is critical for craving and relapse. This study investigated the effects of microinfusion of the muscarinic receptor antagonist scopolamine into the NAc shell on context- and morphine-induced expression of behavioral sensitization. Behavioral sensitization was established by exposure to 5mg/kg morphine once daily for five consecutive days. Expression of behavioral sensitization was induced by saline challenge or 5mg/kg morphine challenge. The results showed that: (a) the muscarinic receptor antagonist scopolamine (10.8μg/rat) microinjected into the NAc shell blocked expression of conditional sensitization; (b) acetylcholinesterase inhibitor huperzine-A (0.5 and 0.1μg/rat), but not scopolamine (10.8μg/rat), microinjected into the NAc shell blocked morphine-induced expression of sensitization; and (c) pre-infusion of scopolamine (10.8μg/rat) reversed the inhibitory effect of huperzine-A (0.5μg/rat) on morphine-induced sensitization. Our findings suggest that muscarinic receptors in the NAc shell play different roles in context-induced and morphine-challenged expression of behavioral sensitization.
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Affiliation(s)
- Xinhe Liu
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing, PR China
| | - Lin Tian
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing, PR China
| | - Ruisi Cui
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing, PR China
| | - Heng Ruan
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing, PR China
| | - Xinwang Li
- Beijing Key Laboratory of Learning and Cognition, Department of Psychology, Capital Normal University, Beijing, PR China.
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10
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LaRese TP, Yan Y, Eipper BA, Mains RE. Using Kalirin conditional knockout mice to distinguish its role in dopamine receptor mediated behaviors. BMC Neurosci 2017; 18:45. [PMID: 28535798 PMCID: PMC5442696 DOI: 10.1186/s12868-017-0363-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 05/19/2017] [Indexed: 01/25/2023] Open
Abstract
Background Mice lacking Kalirin-7 (Kal7KO), a Rho GDP/GTP exchange factor, self-administer cocaine at a higher rate than wildtype mice, and show an exaggerated locomotor response to experimenter-administered cocaine. Kal7, which localizes to post-synaptic densities at glutamatergic synapses, interacts directly with the GluN2B subunit of the N-methyl-d-aspartate (NMDA; GluN) receptor. Consistent with these observations, Kal7 plays an essential role in NMDA receptor dependent long term potentiation and depression, and glutamatergic transmission plays a key role in the response to chronic cocaine. A number of genetic studies have implicated altered Kalirin expression in schizophrenia and other disorders such as Alzheimer’s Disease. Results A comparison of the effects of experimenter-administered cocaine on mice lacking all Kalirin isoforms to its effects on mice lacking only Kalirin-7 identified Kal7 as the key isoform whose deletion produces exaggerated locomotor responses to cocaine. Pretreatment of Kal7KO mice with a low dose of ifenprodil, a selective GluN2B antagonist, eliminated their enhanced locomotor response to cocaine, revealing an important role for GluN2B in this behavior. Selective knockout of Kalirin in dopamine transporter expressing neurons produced a transient enhancement of cocaine-induced locomotion, while knockout of Kalirin in Drd1a- or Drd2-dopamine receptor expressing neurons was without effect. As observed in Kalirin global knockout mice, eliminating Kalirin expression in Drd2-expressing neurons increased exploratory behavior in the elevated zero maze, an effect eliminated by pretreatment with ifenprodil. Conclusions The cocaine-sensitive neuronal pathways which are most sensitive to altered Kalirin function may be the pathways most dependent on GluN2B and Drd2. Electronic supplementary material The online version of this article (doi:10.1186/s12868-017-0363-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Taylor P LaRese
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA
| | - Yan Yan
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA
| | - Betty A Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA.,Departments of Neuroscience and Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA.
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Grasing K. A threshold model for opposing actions of acetylcholine on reward behavior: Molecular mechanisms and implications for treatment of substance abuse disorders. Behav Brain Res 2016; 312:148-62. [PMID: 27316344 DOI: 10.1016/j.bbr.2016.06.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 06/11/2016] [Accepted: 06/13/2016] [Indexed: 12/26/2022]
Abstract
The cholinergic system plays important roles in both learning and addiction. Medications that modify cholinergic tone can have pronounced effects on behaviors reinforced by natural and drug reinforcers. Importantly, enhancing the action of acetylcholine (ACh) in the nucleus accumbens and ventral tegmental area (VTA) dopamine system can either augment or diminish these behaviors. A threshold model is presented that can explain these seemingly contradictory results. Relatively low levels of ACh rise above a lower threshold, facilitating behaviors supported by drugs or natural reinforcers. Further increases in cholinergic tone that rise above a second upper threshold oppose the same behaviors. Accordingly, cholinesterase inhibitors, or agonists for nicotinic or muscarinic receptors, each have the potential to produce biphasic effects on reward behaviors. Pretreatment with either nicotinic or muscarinic antagonists can block drug- or food- reinforced behavior by maintaining cholinergic tone below its lower threshold. Potential threshold mediators include desensitization of nicotinic receptors and biphasic effects of ACh on the firing of medium spiny neurons. Nicotinic receptors with high- and low- affinity appear to play greater roles in reward enhancement and inhibition, respectively. Cholinergic inhibition of natural and drug rewards may serve as mediators of previously described opponent processes. Future studies should evaluate cholinergic agents across a broader range of doses, and include a variety of reinforced behaviors.
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Affiliation(s)
- Kenneth Grasing
- From the Substance Abuse Research Laboratory, 151, Kansas City Veterans Affairs Medical Center, 4801 Linwood Boulevard, Kansas City, MO 64128, United States; From the Division of Clinical Pharmacology, Department of Medicine, University of Kansas School of Medicine, Kansas City, KS 66160, United States.
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Yang W, Yu J, Zhao L, Ma N, Fang Y, Pei F, Mariga AM, Hu Q. Polysaccharides from Flammulina velutipes improve scopolamine-induced impairment of learning and memory of rats. J Funct Foods 2015. [DOI: 10.1016/j.jff.2015.08.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Gonzales KK, Smith Y. Cholinergic interneurons in the dorsal and ventral striatum: anatomical and functional considerations in normal and diseased conditions. Ann N Y Acad Sci 2015; 1349:1-45. [PMID: 25876458 DOI: 10.1111/nyas.12762] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Striatal cholinergic interneurons (ChIs) are central for the processing and reinforcement of reward-related behaviors that are negatively affected in states of altered dopamine transmission, such as in Parkinson's disease or drug addiction. Nevertheless, the development of therapeutic interventions directed at ChIs has been hampered by our limited knowledge of the diverse anatomical and functional characteristics of these neurons in the dorsal and ventral striatum, combined with the lack of pharmacological tools to modulate specific cholinergic receptor subtypes. This review highlights some of the key morphological, synaptic, and functional differences between ChIs of different striatal regions and across species. It also provides an overview of our current knowledge of the cellular localization and function of cholinergic receptor subtypes. The future use of high-resolution anatomical and functional tools to study the synaptic microcircuitry of brain networks, along with the development of specific cholinergic receptor drugs, should help further elucidate the role of striatal ChIs and permit efficient targeting of cholinergic systems in various brain disorders, including Parkinson's disease and addiction.
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Affiliation(s)
- Kalynda K Gonzales
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia.,Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York
| | - Yoland Smith
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia
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Jupp B, Dalley JW. Convergent pharmacological mechanisms in impulsivity and addiction: insights from rodent models. Br J Pharmacol 2014; 171:4729-66. [PMID: 24866553 PMCID: PMC4209940 DOI: 10.1111/bph.12787] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 01/15/2023] Open
Abstract
Research over the last two decades has widely demonstrated that impulsivity, in its various forms, is antecedent to the development of drug addiction and an important behavioural trait underlying the inability of addicts to refrain from continued drug use. Impulsivity describes a variety of rapidly and prematurely expressed behaviours that span several domains from impaired response inhibition to an intolerance of delayed rewards, and is a core symptom of attention deficit hyperactivity disorder (ADHD) and other brain disorders. Various theories have been advanced to explain how impulsivity interacts with addiction both causally and as a consequence of chronic drug abuse; these acknowledge the strong overlaps in neural circuitry and mechanisms between impulsivity and addiction and the seemingly paradoxical treatment of ADHD with stimulant drugs with high abuse potential. Recent years have witnessed unprecedented progress in the elucidation of pharmacological mechanisms underpinning impulsivity. Collectively, this work has significantly improved the prospect for new therapies in ADHD as well as our understanding of the neural mechanisms underlying the shift from recreational drug use to addiction. In this review, we consider the extent to which pharmacological interventions that target impulsive behaviour are also effective in animal models of addiction. We highlight several promising examples of convergence based on empirical findings in rodent-based studies.
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Affiliation(s)
- B Jupp
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of CambridgeCambridge, UK
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, Australia
| | - J W Dalley
- Behavioural and Clinical Neuroscience Institute and Department of Psychology, University of CambridgeCambridge, UK
- Department of Psychiatry, University of CambridgeCambridge, UK
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15
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Lin P, Pratt WE. Inactivation of the nucleus accumbens core or medial shell attenuates reinstatement of sugar-seeking behavior following sugar priming or exposure to food-associated cues. PLoS One 2014; 9:e99301. [PMID: 24910996 PMCID: PMC4049801 DOI: 10.1371/journal.pone.0099301] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/13/2014] [Indexed: 12/12/2022] Open
Abstract
Re-exposure to either palatable food or to conditioned stimuli associated with food is known to reinstate food-seeking after periods of abstinence. The nucleus accumbens core and shell are important for reinstatement in both food- and drug-seeking paradigms, although their potential differential roles have been difficult to delineate due to methodological differences in paradigms across laboratories. The present studies assessed the effects of temporary inactivation of the core or shell on priming- and cue-induced reinstatement of food-seeking in identically-trained rats. Inactivation of either the nucleus accumbens core (Experiment 1A; N = 10) or medial shell (Experiment 1B; N = 12) blocked priming-induced reinstatement in an equivalent manner. Similarly, inactivation of the core or medial shell (Experiments 2A & 2B; N = 11 each) also blocked cue-induced reinstatement, although there was also a significant treatment day X brain region X drug order interaction. Specifically, rats with core inactivation reinstated lever-pressing on the vehicle injection day regardless of whether that was their first or second test, whereas rats that had medial shell inactivation on the first day did not significantly reinstate lever-pressing on the second day of testing (when they received vehicle). Yohimbine, while a reportedly robust pharmacological stressor, was ineffective at inducing reinstatement in the current stress-induced reinstatement procedure. These data suggest that both the nucleus accumbens core and shell serve important roles in reinstatement of food-seeking in response to priming and cues.
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Affiliation(s)
- Peagan Lin
- Department of Psychology, Wake Forest University, Winston-Salem, North Carolina, United States of America
| | - Wayne E. Pratt
- Department of Psychology, Wake Forest University, Winston-Salem, North Carolina, United States of America
- * E-mail:
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Hescham S, Temel Y, Casaca-Carreira J, Arslantas K, Yakkioui Y, Blokland A, Jahanshahi A. A neuroanatomical analysis of the effects of a memory impairing dose of scopolamine in the rat brain using cytochrome c oxidase as principle marker. J Chem Neuroanat 2014; 59-60:1-7. [PMID: 24768696 DOI: 10.1016/j.jchemneu.2014.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 04/08/2014] [Accepted: 04/10/2014] [Indexed: 12/13/2022]
Abstract
Acetylcholine plays a role in mnemonic and attentional processes, but also in locomotor and anxiety-related behavior. Receptor blockage by scopolamine can therefore induce cognitive as well as motor deficits and increase anxiety levels. Here we show that scopolamine, at a dose that has previously been found to affect learning and memory performance (0.1 mg/kg i.p.), has a widespread effect on cytochrome c oxidase histochemistry in various regions of the rat brain. We found a down-regulation of cytochrome c oxidase in the nucleus basalis, in movement-related structures such as the primary motor cortex and the globus pallidus, memory-related structures such as the CA1 subfield of the hippocampus and perirhinal cortex and in anxiety-related structures like the amygdala, which also plays a role in memory. However choline acetyltransferase levels were only affected in the CA1 subfield of the hippocampus and both, choline acetyltransferase and c-Fos expression levels were decreased in the amygdala. These findings corroborate strong cognitive behavioral effects of this drug, but also suggest possible anxiety- and locomotor-related changes in subjects. Moreover, they present histochemical evidence that the effects of scopolamine are not ultimately restricted to cognitive parameters.
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Affiliation(s)
- Sarah Hescham
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands.
| | - Yasin Temel
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Neurosurgery, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands
| | - João Casaca-Carreira
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands
| | - Kemal Arslantas
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Youssef Yakkioui
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Neurosurgery, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands
| | - Arjan Blokland
- Department of Neuropsychology and Psychopharmacology, University of Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands
| | - Ali Jahanshahi
- Department of Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Neurosurgery, Maastricht University, Maastricht, The Netherlands; European Graduate School of Neuroscience (Euron), The Netherlands.
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17
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JIANG X, ZHANG JJ, WANG MY, SUI N. Differential Muscarinic Modulation of Synaptic Transmission in Dorsal and Ventral Regions of the Rat Nucleus Accumbens Core. Physiol Res 2014; 63:135-42. [DOI: 10.33549/physiolres.932518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The nucleus accumbens (NAc) core is critical in the control of motivated behaviors. The muscarinic acetylcholine receptors (mAChRs) modulating the excitatory inputs into the NAc core have been reported to impact such behaviors. Recent studies suggest that ventral and dorsal regions of the NAc core seem to be innervated by distinct populations of glutamatergic projection neurons. To further examine mAChRs modulation of these glutamatergic inputs to the NAc core, we employed intracellular recordings in rat NAc coronal slice preparation to characterize: 1) the effects of muscarine, an mAChRs agonist, on membrane properties of the NAc core neurons; 2) depolarizing synaptic potentials (DPSP) elicited by ventral and dorsal focal electrical stimuli; and 3) paired-pulse response with paired-pulse stimulation. Here we report that the paired-pulse ratio (PPR) elicited by dorsal stimuli was greater than that elicited by ventral stimuli. Bath application of muscarine (1-30 μM) decreased both ventral and dorsal DPSP in a concentration-dependent manner, with no effect on electrophysiological properties of NAc core neurons. Muscarine at 30 μM also elicited larger depression of dorsal DPSP than ventral DPSP. Moreover, muscarine increased the PPR of both dorsal and ventral DPSP. These data indicate that the glutamatergic afferent fibers traversing the dorsal and ventral NAc are separate, and that differential decrease of distinct afferent excitatory neurotransmission onto NAc core neurons may be mediated by presynaptic mechanisms.
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Affiliation(s)
| | | | - M. Y. WANG
- Cell Electrophysiology Laboratory, Wannan Medical College, Wuhu, Anhui, China
| | - N. SUI
- Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
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18
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Gambelunghe C, Bacci M, Aroni K, De Falco F, Ayroldi EM. Cocaine Addiction Treatment and Home Remedies: Use of the Scopolamine Transdermal Patch. Subst Use Misuse 2014; 49:1-6. [PMID: 23924240 DOI: 10.3109/10826084.2013.824477] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Recently, there has been an enormous increase in the number of people seeking treatment for cocaine addiction. Fifteen male cocaine users aged 20-30 years who requested hair analysis from our forensic toxicology laboratory (Perugia, Italy) from March to June 2012, reported using scopolamine without medical supervision to reduce the anxiety associated with cocaine withdrawal. Self-reports were verified with the results obtained from the hair analysis. We discuss whether the use of scopolamine in cocaine abusers could be supported by a neurobiological and pharmacological point of view.
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Affiliation(s)
- Cristiana Gambelunghe
- a 1Department of Clinical and Experimental Medicine, Division of Legal and Sports Medicine, University of Perugia , Perugia, Italy
| | - Mauro Bacci
- a 1Department of Clinical and Experimental Medicine, Division of Legal and Sports Medicine, University of Perugia , Perugia, Italy
| | - Kyriaki Aroni
- a 1Department of Clinical and Experimental Medicine, Division of Legal and Sports Medicine, University of Perugia , Perugia, Italy
| | - Filomena De Falco
- a 1Department of Clinical and Experimental Medicine, Division of Legal and Sports Medicine, University of Perugia , Perugia, Italy
| | - Emira Maria Ayroldi
- b 2Department of Clinical and Experimental Medicine, Division of Pharmacology, University of Perugia , Perugia, Italy
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Acetylcholine as a neuromodulator: cholinergic signaling shapes nervous system function and behavior. Neuron 2012; 76:116-29. [PMID: 23040810 DOI: 10.1016/j.neuron.2012.08.036] [Citation(s) in RCA: 783] [Impact Index Per Article: 65.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2012] [Indexed: 11/22/2022]
Abstract
Acetylcholine in the brain alters neuronal excitability, influences synaptic transmission, induces synaptic plasticity, and coordinates firing of groups of neurons. As a result, it changes the state of neuronal networks throughout the brain and modifies their response to internal and external inputs: the classical role of a neuromodulator. Here, we identify actions of cholinergic signaling on cellular and synaptic properties of neurons in several brain areas and discuss consequences of this signaling on behaviors related to drug abuse, attention, food intake, and affect. The diverse effects of acetylcholine depend on site of release, receptor subtypes, and target neuronal population; however, a common theme is that acetylcholine potentiates behaviors that are adaptive to environmental stimuli and decreases responses to ongoing stimuli that do not require immediate action. The ability of acetylcholine to coordinate the response of neuronal networks in many brain areas makes cholinergic modulation an essential mechanism underlying complex behaviors.
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20
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Increases in αCaMKII phosphorylated on Thr286 in the nucleus accumbens shell but not the core during priming-induced reinstatement of morphine-seeking in rats. Neurosci Lett 2012; 526:39-44. [DOI: 10.1016/j.neulet.2012.07.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Revised: 07/19/2012] [Accepted: 07/23/2012] [Indexed: 12/21/2022]
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Adenosine A2A receptors in the nucleus accumbens bi-directionally alter cocaine seeking in rats. Neuropsychopharmacology 2012; 37:1245-56. [PMID: 22169945 PMCID: PMC3306886 DOI: 10.1038/npp.2011.312] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Repeated cocaine administration enhances dopamine D(2) receptor sensitivity in the mesolimbic dopamine system, which contributes to drug relapse. Adenosine A(2A) receptors are colocalized with D(2) receptors on nucleus accumbens (NAc) medium spiny neurons where they antagonize D(2) receptor activity. Thus, A(2A) receptors represent a target for reducing enhanced D(2) receptor sensitivity that contributes to cocaine relapse. The aim of these studies were to determine the effects of adenosine A(2A) receptor modulation in the NAc on cocaine seeking in rats that were trained to lever press for cocaine. Following at least 15 daily self-administration sessions and 1 week of abstinence, lever pressing was extinguished in daily extinction sessions. We subsequently assessed the effects of intra-NAc core microinjections of the A(2A) receptor agonist, CGS 21680 (4-[2-[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride), and the A(2A) receptor antagonist, MSX-3 (3,7-dihydro-8-[(1E)-2-(3-methoxyphenyl)ethenyl]-7-methyl-3-[3-(phosphonooxy)propyl-1-(2-propynyl)-1H-purine-2,6-dione disodium salt hydrate), in modulating cocaine- and quinpirole-induced reinstatement to cocaine seeking. Intra-NAc pretreatment of CGS 21680 reduced both cocaine- and quinpirole-induced reinstatement. These effects were specific to cocaine reinstatement as intra-NAc CGS 21680 had no effect on sucrose seeking in rats trained to self-administer sucrose pellets. Intra-NAc treatment with MSX-3 modestly reinstated cocaine seeking when given alone, and exacerbated both cocaine- and quinpirole-induced reinstatement. Interestingly, the exacerbation of cocaine seeking produced by MSX-3 was only observed at sub-threshold doses of cocaine and quinpirole, suggesting that removing tonic A(2A) receptor activity enables behaviors mediated by dopamine receptors. Taken together, these findings suggest that A(2A) receptor stimulation reduces, while A(2A) blockade amplifies, D(2) receptor signaling in the NAc that mediates cocaine relapse.
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Fischer-Smith KD, Houston ACW, Rebec GV. Differential effects of cocaine access and withdrawal on glutamate type 1 transporter expression in rat nucleus accumbens core and shell. Neuroscience 2012; 210:333-9. [PMID: 22433294 DOI: 10.1016/j.neuroscience.2012.02.049] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/15/2012] [Accepted: 02/29/2012] [Indexed: 10/28/2022]
Abstract
Cocaine addiction is characterized by compulsive drug seeking, including relapse after a period of withdrawal. The relapse response requires increased glutamate transmission in the nucleus accumbens (NAc). Consistent with this view, glutamate type 1 transporter (GLT1), the transporter responsible for >90% of glutamate uptake, is downregulated in NAc after several days of withdrawal in rats previously trained to self-administer cocaine under limited access conditions (1-2 h/d). Human addiction, however, appears to be better modeled by extending daily drug access (6-8 h/d) and introducing long periods of withdrawal. Here, we determined the combined effects of manipulating cocaine access and withdrawal on GLT1 expression in NAc core and shell. Rats were trained to self-administer cocaine (0.25 mg per intravenous infusion) in daily limited or extended access sessions for 11 days followed by a period of short (1 day) or long (40-45 days) withdrawal. We found that although cocaine withdrawal decreases GLT1 expression in both core and shell, only in core is GLT1 downregulation sensitive to both access and withdrawal. In fact, after long withdrawal, GLT1 in core is downregulated more than in shell in either the limited or extended access condition. Thus, glutamate regulation in core appears to be a critical factor in the drug-seeking behavior that follows relatively long periods of cocaine withdrawal.
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Affiliation(s)
- K D Fischer-Smith
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, USA
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Neural Changes Developed during the Extinction of Cocaine Self-Administration Behavior. Pharmaceuticals (Basel) 2011; 4:1315-27. [PMID: 26791639 PMCID: PMC4060127 DOI: 10.3390/ph4101315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 09/20/2011] [Indexed: 02/06/2023] Open
Abstract
The high rate of recidivism in cocaine addiction after prolonged periods of abstinence poses a significant problem for the effective treatment of this condition. Moreover, the neurobiological basis of this relapse phenomenon remains poorly understood. In this review, we will discuss the evidence currently available regarding the neurobiological changes during the extinction of cocaine self-administration. Specifically, we will focus on alterations in the dopaminergic, opioidergic, glutamatergic, cholinergic, serotoninergic and CRF systems described in self-administration experiments and extinction studies after chronic cocaine administration. We will also discuss the differences related to contingent versus non-contingent cocaine administration, which highlights the importance of environmental cues on drug effects and extinction. The findings discussed in this review may aid the development of more effective therapeutic approaches to treat cocaine relapse.
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Liu XD, Liu Z, Kong QY, Zhang JJ, Wang Y, Yu LC. Different physiological properties of spontaneous excitatory postsynaptic currents in nucleus accumbens shell neurons between adult and juvenile rats. Neurosci Lett 2011; 496:80-3. [PMID: 21501660 DOI: 10.1016/j.neulet.2011.03.086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/11/2011] [Accepted: 03/28/2011] [Indexed: 11/20/2022]
Abstract
Studies have demonstrated the changes of the physiological characteristics of nucleus accumbens (NAc) neurons with the postnatal development of rats. In the present study, spontaneous excitatory postsynaptic currents (sEPSCs) were recorded in the slices of NAc shell (NAcS) of adult and juvenile rats. Our results demonstrate that both the average amplitude of sEPSCs and the average frequency of sEPSCs in the NAcS slices of adult rats decreased significantly than that in juvenile rats. The average half width of sEPSCs in the NAcS slices in adult rats increased significantly than that in juvenile rats. The rise time of sEPSCs, the rise 50 time of sEPSCs and the 10-90 rise time of sEPSCs in the NAcS slices increased significantly in adult rats than that in juvenile rats. The decay time of sEPSCs in the NAcS slices also increased significantly in adult rats than that in juvenile rats. The above results strongly indicate that there are marked changes in the electrophysiological properties of single sEPSC in the NAcS slices of juvenile and adult rats.
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Affiliation(s)
- Xiao-Dong Liu
- Laboratory of Neurobiology and State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, People's Republic of China
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Mains RE, Kiraly DD, Eipper-Mains JE, Ma XM, Eipper BA. Kalrn promoter usage and isoform expression respond to chronic cocaine exposure. BMC Neurosci 2011; 12:20. [PMID: 21329509 PMCID: PMC3048553 DOI: 10.1186/1471-2202-12-20] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Accepted: 02/17/2011] [Indexed: 12/31/2022] Open
Abstract
Background The long-term effects of cocaine on behavior are accompanied by structural changes in excitatory glutamatergic synapses onto the medium spiny neurons of the striatum. The Kalrn gene encodes several functionally distinct isoforms; these multidomain guanine nucleotide exchange factors (GEFs) contain additional domains known to interact with phosphatidylinositides as well as with a number of different proteins. Through their activation of Rho proteins and their interactions with other proteins, the different Kalirin isoforms affect cytoskeletal organization. Chronic exposure of adult male rodents to cocaine increases levels of Kalirin 7 in the striatum. When exposed chronically to cocaine, mice lacking Kalirin 7, the major adult isoform, fail to show an increase in dendritic spine density in the nucleus accumbens, show diminished place preference for cocaine, and exhibit increased locomotor activity in response to cocaine. Results The use of alternate promoters and 3'-terminal exons of the mouse Kalrn gene were investigated using real-time quantitative polymerase chain reaction. While the two most distal full-length Kalrn promoters are used equally in the prefrontal cortex, the more proximal of these promoters accounts for most of the transcripts expressed in the nucleus accumbens. The 3'-terminal exon unique to the Kalirin 7 isoform accounts for a greater percentage of the Kalrn transcripts in prefrontal cortex than in nucleus accumbens. Western blot analyses confirmed these differences. Chronic cocaine treatment increases usage of the promoter encoding the Δ-Kalirin isoforms but does not alter full-length Kalirin promoter usage. Usage of the 3'-terminal exon unique to Kalirin 7 increases following chronic cocaine exposure. Conclusions Kalrn promoter and 3'-terminal exon utilization are region-specific. In the nucleus accumbens, cocaine-mediated alterations in promoter usage and 3'-terminal exon usage favor expression of Kalirin 7 and Δ-Kalirin 7. The Δ-isoform, which lacks a Sec14p domain and four of the nine spectrin-like repeats found in full-length Kalirin isoforms, increases spine headsize without increasing dendritic spine numbers. Thus cocaine-mediated changes in alternative splicing of the Kalrn gene may contribute importantly to the behavioral, morphological and biochemical responses observed.
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Affiliation(s)
- Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030-3401, USA.
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