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Behler AC, George N, Collibee C, Hamilton L, Oleson EB, Thamotharan S. A conceptual framework for queer, black womxn sexual assault survivors: an adaptation of the minoritised stress model. Cult Health Sex 2023; 25:791-802. [PMID: 35900895 DOI: 10.1080/13691058.2022.2089734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 06/10/2022] [Indexed: 06/02/2023]
Abstract
Queer, Black womxn experience sexual assault at an alarming rate in the USA leading to adverse mental and physical health outcomes in survivors. A synthesis of the literature was conducted to understand their unique lived experiences and needs. This article proposes an adapted Meyer's Minoritised Stress framework to understand salient clinical factors impacting Queer, Black womxn sexual assault survivors, including those associated with multiple minoritised identities: Queer-based trauma, race-based trauma, cultural betrayal trauma, and misogynoir. Given the high rates of victimisation, marginalisation and discrimination, psychologists and others working with members of this population should engage with and address these factors to provide culturally responsive, sexually affirming and effective mental health treatment and care.
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Affiliation(s)
| | - Nevita George
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | - Charlene Collibee
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | - Lindsey Hamilton
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | - Erik B Oleson
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | - Sneha Thamotharan
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
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Oleson EB, Khokhar JY. Cannabinoids: Emerging developments in neuropsychopharmacology and biological psychiatry. Prog Neuropsychopharmacol Biol Psychiatry 2021; 110:110305. [PMID: 33737216 DOI: 10.1016/j.pnpbp.2021.110305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cannabinoids from the cannabis plant were one of the earliest psychoactive phytochemicals harnessed by humanity for their medicinal properties and remain one of the most frequently used and misused classes of chemicals in the world. Despite our long-standing history with cannabinoids, much more is said than is known regarding how these molecules influence the brain and behavior. We are in a rapidly evolving discovery phase regarding the neuroscience of cannabinoids. This period of insight began in the mid-1990s when it was discovered that phytocannabinoids (e.g., delta-9-tetrahydrocannabinol) act on G protein-coupled receptors (i.e., CB1/CB2) in the brain to produce their psychoactive effects. Shortly thereafter, it was discovered that endogenous ligands (i.e., endocannabinoids) exist for these receptor targets and, that they are synthetized on demand under a variety of physiological conditions. Thus, we can now study how phytochemicals, endogenous ligands, and synthetic/metabolic enzymes of the endocannabinoid system influence the brain and behavior by activating known receptor targets. Our increased ability to study cannabinoid interactions with the brain and behavior coincides with an increase in international interest in utilizing cannabinoids as a medicine. At the same time, the potency of, and administration routes by which cannabinoids are used is rapidly changing. And, these trends in cannabinoid misuse are producing lasting neural adaptations that have implications for mental health. In this special edition, we will summarize our recent period of discovery regarding how: 1) phytocannabinoids, synthetic cannabinoids and endocannabinoids act on the brain to produce behavioral effects; 2) cannabinoids can be harnessed to produce pharmacotherapeutic utility in the field of medicine; and 3) use of increasingly more cannabinoid variants through unique routes of administration alter the brain and behavior, especially when used in critical developmental periods like pregnancy and adolescence.
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Affiliation(s)
- Erik B Oleson
- Psychology Department, University of Colorado Denver, Denver, CO, USA.
| | - Jibran Y Khokhar
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada
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Oleson EB, Hamilton LR, Gomez DM. Cannabinoid Modulation of Dopamine Release During Motivation, Periodic Reinforcement, Exploratory Behavior, Habit Formation, and Attention. Front Synaptic Neurosci 2021; 13:660218. [PMID: 34177546 PMCID: PMC8222827 DOI: 10.3389/fnsyn.2021.660218] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Motivational and attentional processes energize action sequences to facilitate evolutionary competition and promote behavioral fitness. Decades of neuropharmacology, electrophysiology and electrochemistry research indicate that the mesocorticolimbic DA pathway modulates both motivation and attention. More recently, it was realized that mesocorticolimbic DA function is tightly regulated by the brain's endocannabinoid system and greatly influenced by exogenous cannabinoids-which have been harnessed by humanity for medicinal, ritualistic, and recreational uses for 12,000 years. Exogenous cannabinoids, like the primary psychoactive component of cannabis, delta-9-tetrahydrocannabinol, produce their effects by acting at binding sites for naturally occurring endocannabinoids. The brain's endocannabinoid system consists of two G-protein coupled receptors, endogenous lipid ligands for these receptor targets, and several synthetic and metabolic enzymes involved in their production and degradation. Emerging evidence indicates that the endocannabinoid 2-arachidonoylglycerol is necessary to observe concurrent increases in DA release and motivated behavior. And the historical pharmacology literature indicates a role for cannabinoid signaling in both motivational and attentional processes. While both types of behaviors have been scrutinized under manipulation by either DA or cannabinoid agents, there is considerably less insight into prospective interactions between these two important signaling systems. This review attempts to summate the relevance of cannabinoid modulation of DA release during operant tasks designed to investigate either motivational or attentional control of behavior. We first describe how cannabinoids influence DA release and goal-directed action under a variety of reinforcement contingencies. Then we consider the role that endocannabinoids might play in switching an animal's motivation from a goal-directed action to the search for an alternative outcome, in addition to the formation of long-term habits. Finally, dissociable features of attentional behavior using both the 5-choice serial reaction time task and the attentional set-shifting task are discussed along with their distinct influences by DA and cannabinoids. We end with discussing potential targets for further research regarding DA-cannabinoid interactions within key substrates involved in motivation and attention.
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Affiliation(s)
- Erik B. Oleson
- Department of Psychology, University of Colorado Denver, Denver, CO, United States
| | - Lindsey R. Hamilton
- Department of Psychology, University of Colorado Denver, Denver, CO, United States
| | - Devan M. Gomez
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, United States
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Everett TJ, Gomez DM, Hamilton LR, Oleson EB. Endocannabinoid modulation of dopamine release during reward seeking, interval timing, and avoidance. Prog Neuropsychopharmacol Biol Psychiatry 2021; 104:110031. [PMID: 32663486 DOI: 10.1016/j.pnpbp.2020.110031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/15/2020] [Accepted: 06/28/2020] [Indexed: 01/02/2023]
Abstract
Endocannabinoids (eCBs) are neuromodulators that influence a wide range of neural systems and behaviors. In the current review, we describe our recent research showing how eCBs, particularly 2-arachidonoylglycerol (2-AG), concurrently shape mesolimbic dopamine (DA) release and associated behavior. We will restrict our discussion by emphasizing three distinct behaviors: reward seeking, interval timing, and active avoidance. During reward seeking we find that 2-AG is necessary to observe cue-evoked DA release events that are thought to represent the value of a rewarding outcome. We then describe data showing that 2-AG modulates unique patterns of DA release and behavior observed under conditions of periodic reinforcement. These data are discussed within the context of interval timing and adjunctive behavior. eCB modulation of DA release is also implicated in defensive behavior, including the avoidance of harm. As in reward seeking, our data suggest that the concentration of DA that is evoked by a warning signal can represent the value of an avoidance outcome. And, disrupting eCB signaling concomitantly reduces the concentration of the avoidance value signal and active avoidance. Disruptions in reward seeking, interval timing, and defensive behavior are commonly observed in a variety of movement disorders (e.g., Parkinson's and Huntington's disease) and disorders of motivation (e.g., addiction). We believe our data on eCB-DA interactions have implications for the development of novel pharmacotherapies to treat these disorders. Thus, we conclude by discussing how eCB pharmacology might be harnessed to treat disorders of movement and motivation.
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Affiliation(s)
| | - Devan M Gomez
- Psychology Department, University of Colorado Denver, USA; Department of Biomedical Sciences, Marquette University, USA
| | | | - Erik B Oleson
- Psychology Department, University of Colorado Denver, USA; Integrative Biology Department, University of Colorado Denver, USA.
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Abstract
Cannabis sativa, like all known drugs of abuse, leads to increased dopamine activation within the mesolimbic pathway. Consequent dopamine release within terminal regions of the striatum is a powerful mediator of reward and reinforcement and patterned dopamine release is critical for associative learning processes that are fundamentally involved in addiction. The endocannabinoid system modulates dopamine release at multiple sites, and the receptors, endogenous ligands, and synthetic and metabolic enzymes of the endocannabinoid system may provide key targets for pharmacotherapies to treat disorders of motivation including addiction. Disrupting endocannabinoid signaling decreases drug-induced increases in dopamine release as well those dopamine events evoked by conditioned stimuli during reward seeking. Advances in recording techniques for dopamine are allowing unprecedented examinations of these two interacting systems and elucidating the mechanisms of endocannabinoid modulation of dopamine release in reward and addiction.
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Affiliation(s)
- Kate Z Peters
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Erik B Oleson
- Department of Psychology, University of Colorado, Denver, Colorado 80217-3364, USA
| | - Joseph F Cheer
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Gomez DM, Everett TJ, Hamilton LR, Ranganath A, Cheer JF, Oleson EB. Chronic cannabinoid exposure produces tolerance to the dopamine releasing effects of WIN 55,212-2 and heroin in adult male rats. Neuropharmacology 2021; 182:108374. [PMID: 33115642 PMCID: PMC7836093 DOI: 10.1016/j.neuropharm.2020.108374] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/16/2020] [Accepted: 10/24/2020] [Indexed: 02/06/2023]
Abstract
Synthetic cannabinoids were introduced into recreational drug culture in 2008 and quickly became one of the most commonly abused drugs in the United States. The neurobiological consequences resulting from synthetic cannabinoid repeated exposure remain poorly understood. It is possible that a blunted dopamine (DA) response may lead drug users to consume larger quantities to compensate for this form of neurochemical tolerance. Because the endogenous cannabinoid and opioid systems exhibit considerable cross-talk and cross-tolerance frequently develops following repeated exposure to either opioids or cannabinoids, there is interest in investigating whether a history of synthetic cannabinoid exposure influences the ability of heroin to increase DA release. To test the effects of chronic cannabinoid exposure on cannabinoid- and heroin-evoked DA release, male adult rats were treated with either vehicle or a synthetic cannabinoid (WIN55-212-2; WIN) using an intravenous (IV) dose escalation regimen (0.2-0.8 mg/kg IV over 9 treatments). As predicted, WIN-treated rats showed a rightward shift in the dose-response relationship across all behavioral/physiological measures when compared to vehicle-treated controls. Then, using fast-scan cyclic voltammetry to measure changes in the frequency of transient DA events in the nucleus accumbens shell of awake and freely-moving rats, it was observed that the DA releasing effects of both WIN and heroin were significantly reduced in male rats with a pharmacological history of cannabinoid exposure. These results demonstrate that repeated exposure to the synthetic cannabinoid WIN can produce tolerance to its DA releasing effects and cross-tolerance to the DA releasing effects of heroin.
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Affiliation(s)
- Devan M Gomez
- Psychology Department, University of Colorado Denver, USA; Current: Department of Biomedical Sciences, Marquette University, USA
| | | | | | - Ajit Ranganath
- Department of Neurobiology and Anatomy, University of Maryland Baltimore, USA
| | - Joseph F Cheer
- Department of Neurobiology and Anatomy, University of Maryland Baltimore, USA
| | - Erik B Oleson
- Psychology Department, University of Colorado Denver, USA; Biology Department, University of Colorado Denver, USA.
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Isaacs DP, Leman RP, Everett TJ, Lopez-Beltran H, Hamilton LR, Oleson EB. Buprenorphine is a weak dopamine releaser relative to heroin, but its pretreatment attenuates heroin-evoked dopamine release in rats. Neuropsychopharmacol Rep 2020; 40:355-364. [PMID: 32935483 PMCID: PMC7718284 DOI: 10.1002/npr2.12139] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/13/2020] [Accepted: 08/19/2020] [Indexed: 01/25/2023] Open
Abstract
AIMS The United States of America is currently in an opioid epidemic. Heroin remains the most lethal opioid option with its death rate increasing by over 500% in the last decade. The rewarding and reinforcing effects of heroin are thought to be mediated by its ability to increase dopamine concentration in the nucleus accumbens shell. By activating Gi/o-coupled μ-opioid receptors, opioids are thought to indirectly excite midbrain dopamine neurons by removing an inhibitory GABAergic tone. The partial μ-opioid receptor agonist buprenorphine is a substitution-based therapy for heroin dependence that is thought to produce a steady-state level of μ-opioid receptor activation. But it remains unclear how buprenorphine alters dopamine release relative to heroin and how buprenorphine alters the dopamine-releasing effects of heroin. Because buprenorphine is a partial agonist at the μ-opioid receptor and heroin is a full agonist, we predicted that buprenorphine would function as a weak dopamine releaser relative to heroin, while functioning as a competitive antagonist if administered in advance of heroin. METHODS We performed fast-scan cyclic voltammetry in awake and behaving rats to measure how heroin, buprenorphine HCl, and their combination affect transient dopamine release events in the nucleus accumbens shell. We also performed a complimentary pharmacokinetic analysis comparing opioid plasma levels at time points correlated to our neurochemical findings. RESULTS Both buprenorphine and heroin produced changes in the frequency of transient dopamine release events, although the effect of buprenorphine was weak and only observed at a low dose. In comparison with vehicle, the frequency of dopamine release events maximally increased by ~25% following buprenorphine treatment and by ~60% following heroin treatment. Distinct neuropharmacological effects were observed in the high-dose range. The frequency of dopamine release events increased linearly with heroin dose but biphasically with buprenorphine dose. We also found that buprenorphine pretreatment occluded the dopamine-releasing effects of heroin, but plasma levels of buprenorphine had returned to baseline at this time point. CONCLUSION These findings support the notion that low-dose buprenorphine is a weak dopamine releaser relative to heroin and that buprenorphine pretreatment can block the dopamine-releasing effects of heroin. The finding that high-dose buprenorphine fails to increase dopamine release might explain its relatively low abuse potential among opioid-dependent populations. Because high-dose buprenorphine decreased dopamine release before occluding heroin-evoked dopamine release, and buprenorphine was no longer detected in plasma, we conclude that the mechanisms through which buprenorphine blocks heroin-evoked dopamine release involve multifaceted pharmacokinetic and pharmacodynamic interactions.
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Affiliation(s)
- Dominic P Isaacs
- Psychology Department, University of Colorado, Denver, Colorado, USA.,Department of Bioengineering, University of Colorado, Denver, Colorado, USA
| | - Ryan P Leman
- Psychology Department, University of Colorado, Denver, Colorado, USA
| | - Thomas J Everett
- Psychology Department, University of Colorado, Denver, Colorado, USA
| | | | | | - Erik B Oleson
- Psychology Department, University of Colorado, Denver, Colorado, USA
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Abstract
Benzodiazepines make up a class of psychoactive drugs that act as allosteric co-activators of the inhibitory GABAA receptor. These drugs are useful for the treatment of several psychiatric disorders but also hold considerable abuse liability. Despite the common use and misuse of benzodiazepines, the mechanisms through which these drugs exert their reinforcing effects remain incompletely understood. Transient phasic increases in dopamine levels are believed to play an important role in defining the reinforcing properties of drugs of abuse, and we recently demonstrated that systemic administration of benzodiazepines increased the frequency of these events but concomitantly reduced their amplitude. This observation provides insight into the pharmacological effects of benzodiazepines on dopamine signaling, but the processes through which benzodiazepines drive changes in phasic dopamine signals remain unclear. In these studies, we investigated the mechanisms through which benzodiazepines may reduce the phasic dopamine transient amplitude. We tested the effect of the benzodiazepine diazepam and the GABAA agonist muscimol on evoked dopamine release from nucleus accumbens brain slices using fast scan cyclic voltammetry. We found that both diazepam and muscimol reduce dopamine release and that reductions in dopamine release following GABAA receptor activation can be blocked by co-application of a GABAB receptor antagonist. These results suggest that activation of GABAA receptors in the nucleus accumbens decreases dopamine release by disinhibition of local GABA signaling and subsequent activation of GABAB receptors. Overall, this work provides a putative mechanism through which benzodiazepines reduce the amplitude of phasic dopamine release in vivo.
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Affiliation(s)
- Zachary D. Brodnik
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - Aashita Batra
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - Erik B. Oleson
- Department of Psychology, University of Colorado Denver, Denver, Colorado 80217-3364, United States
| | - Rodrigo A. España
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
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Hamilton LR, Oleson EB. Dopamine release is transiently suppressed during conditioned heroin withdrawal. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.663.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Balolia A, Tanner MK, Moya NA, Wiseman JR, Loetz EC, Davis JKP, Jaime J, Oleson EB, Greenwood B. Role of the Dorsal Striatum in Fear Extinction and Relapse. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.738.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Everett T, Leman R, Lopez‐Beltran H, Chaman O, Isaacs D, Oleson EB. Commonly Abused Drugs Differentially Increase the Frequency and Amplitude of Accumbal Transient Dopamine Release Events. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.lb81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Roberts JB, Oleson EB. A characterization of behavior and monoamine interactions during conditioned avoidance maintained in a within‐session behavioral economic avoidance task. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.805.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hake HS, Davis JKP, Wood RR, Tanner MK, Loetz EC, Sanchez A, Ostrovskyy M, Oleson EB, Grigsby J, Doblin R, Greenwood BN. 3,4-methylenedioxymethamphetamine (MDMA) impairs the extinction and reconsolidation of fear memory in rats. Physiol Behav 2019; 199:343-350. [PMID: 30529341 PMCID: PMC6557441 DOI: 10.1016/j.physbeh.2018.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 01/04/2023]
Abstract
Clinical trials have demonstrated that 3,4-methylenedioxymethamphetamine (MDMA) paired with psychotherapy is more effective at reducing symptoms of post-traumatic stress disorder (PTSD) than psychotherapy or pharmacotherapy, alone or in combination. The processes through which MDMA acts to enhance psychotherapy are not well understood. Given that fear memories contribute to PTSD symptomology, MDMA could augment psychotherapy by targeting fear memories. The current studies investigated the effects of a single administration of MDMA on extinction and reconsolidation of cued and contextual fear memory in adult, male Long-Evans rats. Rats were exposed to contextual or auditory fear conditioning followed by systemic administration of saline or varying doses of MDMA (between 1 and 10 mg/kg) either 30 min before fear extinction training or immediately after brief fear memory retrieval (i.e. during the reconsolidation phase). MDMA administered prior to fear extinction training failed to enhance fear extinction memory, and in fact impaired drug-free cued fear extinction recall without impacting later fear relapse. MDMA administered during the reconsolidation phase, but not outside of the reconsolidation phase, produced a delayed and persistent reduction in conditioned fear. These findings are consistent with a general memory-disrupting effect of MDMA and suggest that MDMA could augment psychotherapy by modifying fear memories during reconsolidation without necessarily enhancing their extinction.
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Affiliation(s)
- Holly S Hake
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Jazmyne K P Davis
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - River R Wood
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Margaret K Tanner
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Esteban C Loetz
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Anais Sanchez
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Mykola Ostrovskyy
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Erik B Oleson
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | - Jim Grigsby
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA; Department of Medicine, University of Colorado Denver School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Rick Doblin
- Multidisciplinary Association for Psychedelic Studies, 1115 Mission Street, Santa Cruz, CA 95060-9989, USA
| | - Benjamin N Greenwood
- Department of Psychology, University of Colorado Denver, PO Box 173364, Denver, CO 80217-3364, USA.
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Wenzel JM, Oleson EB, Gove WN, Cole AB, Gyawali U, Dantrassy HM, Bluett RJ, Dryanovski DI, Stuber GD, Deisseroth K, Mathur BN, Patel S, Lupica CR, Cheer JF. Phasic Dopamine Signals in the Nucleus Accumbens that Cause Active Avoidance Require Endocannabinoid Mobilization in the Midbrain. Curr Biol 2018; 28:1392-1404.e5. [PMID: 29681476 DOI: 10.1016/j.cub.2018.03.037] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/12/2018] [Accepted: 03/15/2018] [Indexed: 11/17/2022]
Abstract
Phasic dopamine (DA) release accompanies approach toward appetitive cues. However, a role for DA in the active avoidance of negative events remains undetermined. Warning signals informing footshock avoidance are associated with accumbal DA release, whereas depression of DA is observed with unavoidable footshock. Here, we reveal a causal role of phasic DA in active avoidance learning; specifically, optogenetic activation of DA neurons facilitates avoidance, whereas optical inhibition of these cells attenuates it. Furthermore, stimulation of DA neurons during presentation of a fear-conditioned cue accelerates the extinction of a passive defensive behavior (i.e., freezing). Dopaminergic control of avoidance requires endocannabinoids (eCBs), as perturbing eCB signaling in the midbrain disrupts avoidance, which is rescued by optical stimulation of DA neurons. Interestingly, once the avoidance task is learned, neither DA nor eCB manipulations affect performance, suggesting that once acquisition occurs, expression of this behavior is subserved by other anatomical frameworks. Our findings establish an instrumental role for DA release in learning active responses to aversive stimuli and its control by eCB signaling.
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Affiliation(s)
- Jennifer M Wenzel
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erik B Oleson
- Department of Psychology, University of Colorado, Denver, CO 80204, USA
| | - Willard N Gove
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Anthony B Cole
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Utsav Gyawali
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Hannah M Dantrassy
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rebecca J Bluett
- Vanderbilt Brain Institute and Department of Psychiatry, Vanderbilt University, Nashville, TN 37235, USA
| | - Dilyan I Dryanovski
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Garret D Stuber
- Department of Psychiatry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Brian N Mathur
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Sachin Patel
- Vanderbilt Brain Institute and Department of Psychiatry, Vanderbilt University, Nashville, TN 37235, USA; Vanderbilt School of Medicine and Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37235, USA
| | - Carl R Lupica
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Pultorak KJ, Schelp SA, Isaacs DP, Krzystyniak G, Oleson EB. A Transient Dopamine Signal Represents Avoidance Value and Causally Influences the Demand to Avoid. eNeuro 2018; 5:ENEURO.0058-18.2018. [PMID: 29766047 PMCID: PMC5952648 DOI: 10.1523/eneuro.0058-18.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/05/2018] [Accepted: 04/05/2018] [Indexed: 12/20/2022] Open
Abstract
While an extensive literature supports the notion that mesocorticolimbic dopamine plays a role in negative reinforcement, recent evidence suggests that dopamine exclusively encodes the value of positive reinforcement. In the present study, we employed a behavioral economics approach to investigate whether dopamine plays a role in the valuation of negative reinforcement. Using rats as subjects, we first applied fast-scan cyclic voltammetry (FSCV) to determine that dopamine concentration decreases with the number of lever presses required to avoid electrical footshock (i.e., the economic price of avoidance). Analysis of the rate of decay of avoidance demand curves, which depict an inverse relationship between avoidance and increasing price, allows for inference of the worth an animal places on avoidance outcomes. Rapidly decaying demand curves indicate increased price sensitivity, or low worth placed on avoidance outcomes, while slow rates of decay indicate reduced price sensitivity, or greater worth placed on avoidance outcomes. We therefore used optogenetics to assess how inducing dopamine release causally modifies the demand to avoid electrical footshock in an economic setting. Increasing release at an avoidance predictive cue made animals more sensitive to price, consistent with a negative reward prediction error (i.e., the animal perceives they received a worse outcome than expected). Increasing release at avoidance made animals less sensitive to price, consistent with a positive reward prediction error (i.e., the animal perceives they received a better outcome than expected). These data demonstrate that transient dopamine release events represent the value of avoidance outcomes and can predictably modify the demand to avoid.
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Schelp SA, Pultorak KJ, Rakowski DR, Gomez DM, Krzystyniak G, Das R, Oleson EB. A transient dopamine signal encodes subjective value and causally influences demand in an economic context. Proc Natl Acad Sci U S A 2017; 114:E11303-E11312. [PMID: 29109253 PMCID: PMC5748169 DOI: 10.1073/pnas.1706969114] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The mesolimbic dopamine system is strongly implicated in motivational processes. Currently accepted theories suggest that transient mesolimbic dopamine release events energize reward seeking and encode reward value. During the pursuit of reward, critical associations are formed between the reward and cues that predict its availability. Conditioned by these experiences, dopamine neurons begin to fire upon the earliest presentation of a cue, and again at the receipt of reward. The resulting dopamine concentration scales proportionally to the value of the reward. In this study, we used a behavioral economics approach to quantify how transient dopamine release events scale with price and causally alter price sensitivity. We presented sucrose to rats across a range of prices and modeled the resulting demand curves to estimate price sensitivity. Using fast-scan cyclic voltammetry, we determined that the concentration of accumbal dopamine time-locked to cue presentation decreased with price. These data confirm and extend the notion that dopamine release events originating in the ventral tegmental area encode subjective value. Using optogenetics to augment dopamine concentration, we found that enhancing dopamine release at cue made demand more sensitive to price and decreased dopamine concentration at reward delivery. From these observations, we infer that value is decreased because of a negative reward prediction error (i.e., the animal receives less than expected). Conversely, enhancing dopamine at reward made demand less sensitive to price. We attribute this finding to a positive reward prediction error, whereby the animal perceives they received a better value than anticipated.
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Affiliation(s)
- Scott A Schelp
- Psychology Department, University of Colorado Denver, Denver, CO 80217
| | | | - Dylan R Rakowski
- Psychology Department, University of Colorado Denver, Denver, CO 80217
| | - Devan M Gomez
- Psychology Department, University of Colorado Denver, Denver, CO 80217
| | | | - Raibatak Das
- Psychology Department, University of Colorado Denver, Denver, CO 80217
| | - Erik B Oleson
- Psychology Department, University of Colorado Denver, Denver, CO 80217
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Schelp SA, Brodnik ZD, Rakowski DR, Pultorak KJ, Sambells AT, España RA, Oleson EB. Diazepam Concurrently Increases the Frequency and Decreases the Amplitude of Transient Dopamine Release Events in the Nucleus Accumbens. J Pharmacol Exp Ther 2017; 364:145-155. [PMID: 29054857 DOI: 10.1124/jpet.117.241802] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 10/04/2017] [Indexed: 01/01/2023] Open
Abstract
Benzodiazepines are commonly prescribed anxiolytics that pose abuse liability in susceptible individuals. Although it is well established that all drugs of abuse increase brain dopamine levels, and benzodiazepines are allosteric modulators of the GABAA receptor, it remains unclear how they alter dopamine release. Using in vivo fast-scan cyclic voltammetry, we measured diazepam-induced changes in the frequency and amplitude of transient dopamine release events. We found that diazepam concurrently increases the frequency and decreases the amplitude of transient dopamine release events in the awake and freely moving rat. The time course during which diazepam altered the frequency and amplitude of dopamine release events diverged, with the decreased amplitude effect being shorter lived than the increase in frequency, but both showing similar rates of onset. We conclude that diazepam increases the frequency of accumbal dopamine release events by disinhibiting dopamine neurons, but also decreases their amplitude. We speculate that the modest abuse liability of benzodiazepines is due to their ability to decrease the amplitude of dopamine release events in addition to increasing their frequency.
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Affiliation(s)
- Scott A Schelp
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Zachary D Brodnik
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Dylan R Rakowski
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Katherine J Pultorak
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Asha T Sambells
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Rodrigo A España
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
| | - Erik B Oleson
- University of Colorado Denver, Department of Psychology, Denver, Colorado (S.A.S., D.R.R., K.J.P., A.T.S., E.B.O.) and Drexel University College of Medicine, Department of Neurobiology and Anatomy, Philadelphia, Pennsylvania (Z.D.R., R.A.E.)
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Budygin EA, Oleson EB, Lee YB, Blume LC, Bruno MJ, Howlett AC, Thompson AC, Bass CE. Acute Depletion of D2 Receptors from the Rat Substantia Nigra Alters Dopamine Kinetics in the Dorsal Striatum and Drug Responsivity. Front Behav Neurosci 2017; 10:248. [PMID: 28154530 PMCID: PMC5243821 DOI: 10.3389/fnbeh.2016.00248] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/19/2016] [Indexed: 01/20/2023] Open
Abstract
Recent studies have used conditional knockout mice to selectively delete the D2 autoreceptor; however, these approaches result in global deletion of D2 autoreceptors early in development. The present study takes a different approach using RNA interference (RNAi) to knockdown the expression of the D2 receptors (D2R) in the substantia nigra (SN), including dopaminergic neurons, which project primarily to the dorsal striatum (dStr) in adult rats. This approach restricts the knockdown primarily to nigrostriatal pathways, leaving mesolimbic D2 autoreceptors intact. Analyses of dopamine (DA) kinetics in the dStr reveal a decrease in DA transporter (DAT) function in the knockdown rats, an effect not observed in D2 autoreceptor knockout mouse models. SN D2 knockdown rats exhibit a behavioral phenotype characterized by persistent enhancement of locomotor activity in a familiar open field, reduced locomotor responsiveness to high doses of cocaine and the ability to overcome haloperidol-induced immobility on the bar test. Together these results demonstrate that presynaptic D2R can be depleted from specific neuronal populations and implicates nigrostriatal D2R in different behavioral responses to psychotropic drugs.
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Affiliation(s)
- Evgeny A Budygin
- Department of Neurobiology and Anatomy, Wake Forest School of MedicineWinston Salem, NC, USA; Institute of Translational Biomedicine, St. Petersburg State UniversitySt. Petersburg, Russia
| | - Erik B Oleson
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Yun Beom Lee
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
| | - Lawrence C Blume
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Michael J Bruno
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
| | - Allyn C Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine Winston Salem, NC, USA
| | - Alexis C Thompson
- Research Institute on Addictions, University at Buffalo Buffalo, NY, USA
| | - Caroline E Bass
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
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Wenzel JM, Rauscher NA, Cheer JF, Oleson EB. A role for phasic dopamine release within the nucleus accumbens in encoding aversion: a review of the neurochemical literature. ACS Chem Neurosci 2015; 6:16-26. [PMID: 25491156 DOI: 10.1021/cn500255p] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Survival is dictated by an organism's fitness in approaching positive stimuli and avoiding harm. While a rich literature outlines a role for mesolimbic dopamine in reward and appetitive behaviors, dopamine's involvement in aversion and avoidance behaviors remains controversial. Debate surrounding dopamine's function in the processing of negative stimuli likely stems from conflicting results reported by single-unit electrophysiological studies. Indeed, a number of studies suggest that midbrain dopaminergic cells are inhibited by the presentation of negative or fearful stimuli, while others report no change, or even an increase, in their activity. These disparate results may be due to population heterogeneity. Recent evidence demonstrates that midbrain dopamine neurons are heterogeneous in their projection targets, responses to environmental stimuli, pharmacology, and influences on motivated behavior. Thus, in order to assemble an accurate account of dopamine function during aversive stimulus experience and related behavior, it is necessary to examine the functional output of dopamine neural activity at mesolimbic terminal regions. This Review presents a growing body of evidence that dopamine release in the nucleus accumbens encodes not only reward, but also aversion. For example, our laboratory recently utilized fast-scan cyclic voltammetry to show that real-time changes in accumbal dopamine release are detected when animals are presented with predictors of aversion and its avoidance. These data, along with other reports, support a considerably more nuanced view of dopamine neuron function, wherein accumbal dopamine release is differentially modulated by positive and negative affective stimuli to promote adaptive behaviors.
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Affiliation(s)
| | - Noah A. Rauscher
- Department
of Psychology, University of Colorado, Denver, Colorado 80015, United States
| | | | - Erik B. Oleson
- Department
of Psychology, University of Colorado, Denver, Colorado 80015, United States
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Oleson EB, Cachope R, Fitoussi A, Cheer JF. Tales from the dark side: do neuromodulators of drug withdrawal require changes in endocannabinoid tone? Prog Neuropsychopharmacol Biol Psychiatry 2014; 52:17-23. [PMID: 23911441 PMCID: PMC3874071 DOI: 10.1016/j.pnpbp.2013.07.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 07/15/2013] [Accepted: 07/23/2013] [Indexed: 10/26/2022]
Abstract
Environmental and interoceptive cues are theorized to serve as 'signals' that motivate drug seeking and effects that may be augmented in the withdrawn state. Phasic dopamine release events are observed in the nucleus accumbens in response to such motivational salient stimuli and are thought to be necessary for drug-associated cues to trigger craving. We recently demonstrated how dopamine neurons encode stimuli conditioned to a negative event, as might occur during conditioned withdrawal, and stimuli predicting the avoidance of negative events, as might occur as an addict seeks out drugs to prevent withdrawal. In this review we first discuss how the subsecond dopamine release events might process conditioned withdrawal and drug seeking driven by negative reinforcement processes within the context of our dopamine data obtained during conditioned avoidance procedures. We next describe how the endocannabinoid system modulates phasic dopamine release events and how it might be harnessed to treat negative affective states in addiction. Specifically, we have demonstrated that endocannabinoids in the ventral tegmentum sculpt cue-induced accumbal surges in dopamine release and, therefore, may also be mobilized during drug withdrawal.
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Affiliation(s)
- Erik B. Oleson
- University of Maryland, School of Medicine, 20 Penn St. Baltimore MD 21201,University of Colorado Denver, P.O. Box 173364, Denver, CO 80217
| | - Roger Cachope
- University of Maryland, School of Medicine, 20 Penn St. Baltimore MD 21201
| | - Aurelie Fitoussi
- University of Maryland, School of Medicine, 20 Penn St. Baltimore MD 21201
| | - Joseph F. Cheer
- University of Maryland, School of Medicine, 20 Penn St. Baltimore MD 21201
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Oleson EB, Cachope R, Fitoussi A, Tsutsui K, Wu S, Gallegos JA, Cheer JF. Cannabinoid receptor activation shifts temporally engendered patterns of dopamine release. Neuropsychopharmacology 2014; 39:1441-52. [PMID: 24345819 PMCID: PMC3988547 DOI: 10.1038/npp.2013.340] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 11/11/2013] [Accepted: 12/08/2013] [Indexed: 11/09/2022]
Abstract
The ability to discern temporally pertinent environmental events is essential for the generation of adaptive behavior in conventional tasks, and our overall survival. Cannabinoids are thought to disrupt temporally controlled behaviors by interfering with dedicated brain timing networks. Cannabinoids also increase dopamine release within the mesolimbic system, a neural pathway generally implicated in timing behavior. Timing can be assessed using fixed-interval (FI) schedules, which reinforce behavior on the basis of time. To date, it remains unknown how cannabinoids modulate dopamine release when responding under FI conditions, and for that matter, how subsecond dopamine release is related to time in these tasks. In the present study, we hypothesized that cannabinoids would accelerate timing behavior in an FI task while concurrently augmenting a temporally relevant pattern of dopamine release. To assess this possibility, we measured subsecond dopamine concentrations in the nucleus accumbens while mice responded for food under the influence of the cannabinoid agonist WIN 55,212-2 in an FI task. Our data reveal that accumbal dopamine concentrations decrease proportionally to interval duration--suggesting that dopamine encodes time in FI tasks. We further demonstrate that WIN 55,212-2 dose-dependently increases dopamine release and accelerates a temporal behavioral response pattern in a CB1 receptor-dependent manner--suggesting that cannabinoid receptor activation modifies timing behavior, in part, by augmenting time-engendered patterns of dopamine release. Additional investigation uncovered a specific role for endogenous cannabinoid tone in timing behavior, as elevations in 2-arachidonoylglycerol, but not anandamide, significantly accelerated the temporal response pattern in a manner akin to WIN 55,212-2.
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Affiliation(s)
- Erik B Oleson
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA,University of Colorado Denver, Denver, CO, USA
| | - Roger Cachope
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aurelie Fitoussi
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kimberly Tsutsui
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sharon Wu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD 21201, USA, Tel: +1 410 706 0112, Fax: +1 410 706 2512, E-mail:
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Hernandez G, Oleson EB, Gentry RN, Abbas Z, Bernstein DL, Arvanitogiannis A, Cheer JF. Endocannabinoids promote cocaine-induced impulsivity and its rapid dopaminergic correlates. Biol Psychiatry 2014; 75:487-98. [PMID: 24138924 PMCID: PMC3943889 DOI: 10.1016/j.biopsych.2013.09.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 08/13/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Impaired decision making, a hallmark of addiction, is hypothesized to arise from maladaptive plasticity in the mesolimbic dopamine pathway. The endocannabinoid system modulates dopamine activity through activation of cannabinoid type 1 receptors (CB1Rs). Here, we investigated whether impulsive behavior observed following cocaine exposure requires CB1R activation. METHODS We trained rats in a delay-discounting task. Following acquisition of stable performance, rats were exposed to cocaine (10 mg/kg, intraperitoneal) every other day for 14 days and locomotor activity was measured. Two days later, delay-discounting performance was re-evaluated. To assess reversal of impulsivity, injections of a CB1R antagonist (1.5 mg/kg, intraperitoneal) or vehicle were given 30 minutes before the task. During the second experiment, aimed at preventing impulsivity rather than reversing it, CB1Rs were antagonized before each cocaine injection. In this experiment, subsecond dopamine release was measured in the nucleus accumbens during delay-discounting sessions before and after cocaine treatment. RESULTS Blockade of CB1Rs reversed and prevented cocaine-induced impulsivity. Electrochemical results showed that during baseline and following disruption of endocannabinoid signaling, there was a robust increase in dopamine for immediate large rewards compared with immediate small rewards, but this effect reversed when the delay for the large reward was 10 seconds. In contrast, dopamine release always increased for one-pellet options at minimal or moderate delays in vehicle-treated rats. CONCLUSIONS Endocannabinoids play a critical role in changes associated with cocaine exposure. Cannabinoid type 1 receptor blockade may thus counteract maladaptive alterations in afferents to dopamine neurons, thereby preventing changes in dopaminergic activity underlying a loss of self-control.
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Affiliation(s)
| | - Erik B. Oleson
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, (Baltimore-Maryland)
| | - Ronny N. Gentry
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, (Baltimore-Maryland)
| | - Zarish Abbas
- Center for Studies in Behavioral Neurobiology, Concordia University (Montréal-Quebec)
| | - David L. Bernstein
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, (Baltimore-Maryland)
| | - A. Arvanitogiannis
- Center for Studies in Behavioral Neurobiology, Concordia University (Montréal-Quebec)
| | - Joseph F. Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, (Baltimore-Maryland),Department of Psychiatry, University of Maryland School of Medicine, (Baltimore-Maryland),Corresponding Author: 20 Penn Street, Baltimore MD, 21201. Phone: (410) 706 0112/Fax: (410) 706 2512.
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Wang B, You ZB, Oleson EB, Cheer JF, Myal S, Wise RA. Conditioned contribution of peripheral cocaine actions to cocaine reward and cocaine-seeking. Neuropsychopharmacology 2013; 38:1763-9. [PMID: 23535778 PMCID: PMC3717534 DOI: 10.1038/npp.2013.75] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 03/13/2013] [Accepted: 03/13/2013] [Indexed: 11/09/2022]
Abstract
Cocaine has actions in the peripheral nervous system that reliably precede--and thus predict--its soon-to-follow central rewarding effects. In cocaine-experienced animals, the peripheral cocaine signal is relayed to the central nervous system, triggering excitatory input to the ventral tegmental origin of the mesocorticolimbic dopamine system, the system that mediates the rewarding effects of the drug. We used cocaine methiodide, a cocaine analog that does not cross the blood-brain barrier, to isolate the peripheral actions of cocaine and determine their central and behavioral effects in animals first trained to lever-press for cocaine hydrochloride (the centrally acting and abused form of the drug). We first confirmed with fast-scan cyclic voltammetry that cocaine methiodide causes rapid dopamine release from dopamine terminals in cocaine hydrochloride-trained rats. We then compared the ability of cocaine hydrochloride and cocaine methiodide to establish conditioned place preferences in rats with self-administration experience. While cocaine hydrochloride established stronger place preferences, cocaine methiodide was also effective and its effectiveness increased (incubated) over weeks of cocaine abstinence. Cocaine self-administration was extinguished when cocaine methiodide or saline was substituted for cocaine hydrochloride in the intravenous self-administration paradigm, but cocaine hydrochloride and cocaine methiodide each reinstated non-rewarded lever-pressing after extinction. Rats extinguished by cocaine methiodide substitution showed weaker cocaine-induced reinstatement than rats extinguished by saline substitution. These findings suggest that the conditioned peripheral effects of cocaine can contribute significantly to cocaine-induced (but not stress-induced) cocaine craving, and also suggest the cocaine cue as an important target for cue-exposure therapies for cocaine addiction.
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Affiliation(s)
- Bin Wang
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD, USA
| | - Zhi-Bing You
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD, USA
| | - Erik B Oleson
- University of Maryland School of Medicine Department of Anatomy and Neurobiology Baltimore, MD, USA
| | - Joseph F Cheer
- University of Maryland School of Medicine Department of Anatomy and Neurobiology Baltimore, MD, USA
| | - Stephanie Myal
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD, USA
| | - Roy A Wise
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, MD, USA,Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, 5500 Nathan Shock Drive, 251 Bayview Boulevard, Baltimore, MD 21224, USA, Tel: +1 443 740 2460, Fax: +1 443 740 2827, E-mail:
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Abstract
Using shock avoidance procedures to study conditioned behavioral responses has a rich history within the field of experimental psychology. Such experiments led to the formulation of the general concept of negative reinforcement and specific theories attempting to explain escape and avoidance behavior, or why animals choose to either terminate or prevent the presentation of an aversive event. For example, the two-factor theory of avoidance holds that cues preceding an aversive event begin to evoke conditioned fear responses, and these conditioned fear responses reinforce the instrumental avoidance response. Current neuroscientific advances are providing new perspectives into this historical literature. Due to its well-established role in reinforcement processes and behavioral control, the mesolimbic dopamine system presented itself as a logical starting point in the search for neural correlates of avoidance and escape behavior. We recently demonstrated that phasic dopamine release events are inhibited by stimuli associated with aversive events but increased by stimuli preceding the successful avoidance of the aversive event. The latter observation is inconsistent with the second component of the two-factor theory of avoidance and; therefore, led us propose a new theoretical explanation of conditioned avoidance: (1) fear is initially conditioned to the warning signal and dopamine computes this fear association as a decrease in release, (2) the warning signal, now capable of producing a negative emotional state, suppresses dopamine release and behavior, (3) over repeated trials the warning signal becomes associated with safety rather than fear; dopaminergic neurons already compute safety as an increase in release and begin to encode the warning signal as the earliest predictor of safety (4) the warning signal now promotes conditioned avoidance via dopaminergic modulation of the brain's incentive-motivational circuitry.
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Affiliation(s)
- Erik B Oleson
- Department of Anatomy and Neurobiology, School of Medicine, University of Maryland Baltimore, MD, USA
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Oleson EB, Cheer JF. Paradoxical effects of the endocannabinoid uptake inhibitor VDM11 on accumbal neural encoding of reward predictive cues. Synapse 2012; 66:984-8. [PMID: 22807176 PMCID: PMC3440520 DOI: 10.1002/syn.21587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/13/2012] [Accepted: 07/12/2012] [Indexed: 11/08/2022]
Abstract
A growing body of evidence implicates the endocannabinoid (eCB) system in brain reward function. Previous studies show that antagonizing eCB transmission decreases reward-directed behavior and nucleus accumbens (NAc) encoding of reward predictive cues. We, therefore, hypothesized that elevating eCB levels would uniformly facilitate NAc neural encoding of reward predictive cues and reward-directed behavior. Contrary to our expectations, the eCB transport uptake inhibitor, VDM11, dose dependently decreased both measures.
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Affiliation(s)
- Erik B. Oleson
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Joseph F. Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Abstract
Increases in mesolimbic dopamine transmission are observed when animals are treated with all known drugs of abuse, including cannabis, and to conditioned stimuli predicting their availability. In contrast, decreases in mesolimbic dopamine function are observed during drug withdrawal, including cannabis-withdrawal syndrome. Thus, despite general misconceptions that cannabis is unique from other drugs of abuse, cannabis exerts identical effects on the mesolimbic dopamine system. The recent discovery that endogenous cannabinoids modulate the mesolimbic dopamine system, however, might be exploited for the development of potential pharmacotherapies designed to treat disorders of motivation. Indeed, disrupting endocannabinoid signaling decreases drug-induced increases in dopamine release in addition to dopamine concentrations evoked by conditioned stimuli during reward seeking.
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Affiliation(s)
- Erik B Oleson
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Lee AM, Oleson EB, Diergaarde L, Cheer JF, Pattij T. Cannabinoids and value-based decision making: implications for neurodegenerative disorders. ACTA ACUST UNITED AC 2012; 2:131-138. [PMID: 23162787 DOI: 10.1016/j.baga.2012.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In recent years, disturbances in cognitive function have been increasingly recognized as important symptomatic phenomena in neurodegenerative diseases, including Parkinson's Disease (PD). Value-based decision making in particular is an important executive cognitive function that is not only impaired in patients with PD, but also shares neural substrates with PD in basal ganglia structures and the dopamine system. Interestingly, the endogenous cannabinoid system modulates dopamine function and subsequently value-based decision making. This review will provide an overview of the interdisciplinary research that has influenced our understanding of value-based decision making and the role of dopamine, particularly in the context of reinforcement learning theories, as well as recent animal and human studies that demonstrate the modulatory role of activation of cannabinoid receptors by exogenous agonists or their naturally occurring ligands. The implications of this research for the symptomatology of and potential treatments for PD are also discussed.
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Affiliation(s)
- Angela M Lee
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU university medical center, Amsterdam, the Netherlands
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Oleson EB, Beckert MV, Morra JT, Lansink CS, Cachope R, Abdullah RA, Loriaux AL, Schetters D, Pattij T, Roitman MF, Lichtman AH, Cheer JF. Endocannabinoids shape accumbal encoding of cue-motivated behavior via CB1 receptor activation in the ventral tegmentum. Neuron 2012; 73:360-73. [PMID: 22284189 DOI: 10.1016/j.neuron.2011.11.018] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2011] [Indexed: 01/01/2023]
Abstract
Transient increases in nucleus accumbens (NAc) dopamine concentration are observed when animals are presented with motivationally salient stimuli and are theorized to energize reward seeking. They arise from high-frequency firing of dopamine neurons in the ventral tegmental area (VTA), which also results in the release of endocannabinoids from dopamine cell bodies. In this context, endocannabinoids are thought to regulate reward seeking by modulating dopamine signaling, although a direct link has never been demonstrated. To test this, we pharmacologically manipulated endocannabinoid neurotransmission in the VTA while measuring transient changes in dopamine concentration in the NAc during reward seeking. Disrupting endocannabinoid signaling dramatically reduced, whereas augmenting levels of the endocannabinoid 2-arachidonoylglycerol (2AG) increased, cue-evoked dopamine concentrations and reward seeking. These data suggest that 2AG in the VTA regulates reward seeking by sculpting ethologically relevant patterns of dopamine release during reward-directed behavior.
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Affiliation(s)
- Erik B Oleson
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Oleson EB, Ferris MJ, España RA, Harp J, Jones SR. Effects of the histamine H₁ receptor antagonist and benztropine analog diphenylpyraline on dopamine uptake, locomotion and reward. Eur J Pharmacol 2012; 683:161-5. [PMID: 22445882 DOI: 10.1016/j.ejphar.2012.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/22/2012] [Accepted: 03/04/2012] [Indexed: 11/28/2022]
Abstract
Diphenylpyraline hydrochloride (DPP) is an internationally available antihistamine that produces therapeutic antiallergic effects by binding to histamine H₁ receptors. The complete neuropharmacological and behavioral profile of DPP, however, remains uncharacterized. Here we describe studies that suggest DPP may fit the profile of a potential agonist replacement medication for cocaine addiction. Aside from producing the desired histamine reducing effects, many antihistamines can also elicit psychomotor activation and reward, both of which are associated with increased dopamine concentrations in the nucleus accumbens (NAc). The primary aim of this study was to investigate the potential ability of DPP to inhibit the dopamine transporter, thereby leading to elevated dopamine concentrations in the NAc in a manner similar to cocaine and other psychostimulants. The psychomotor activating and rewarding effects of DPP were also investigated. For comparative purposes cocaine, a known dopamine transporter inhibitor, psychostimulant and drug of abuse, was used as a positive control. As predicted, both cocaine (15 mg/kg) and an equimolar dose of DPP (14 mg/kg) significantly inhibited dopamine uptake in the NAc in vivo and produced locomotor activation, although the time-course of pharmacological effects of the two drugs was different. In comparison to cocaine, DPP showed a prolonged effect on dopamine uptake and locomotion. Furthermore, cocaine, but not DPP, produced significant conditioned place preference, a measure of drug reward. The finding that DPP functions as a potent dopamine uptake inhibitor without producing significant rewarding effects suggests that DPP merits further study as a potential candidate as an agonist pharmacotherapy for cocaine addiction.
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Affiliation(s)
- Erik B Oleson
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
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Abstract
Cocaine self-administration provides a methodology allowing researchers to study changes in distinct aspects of drug-taking behavior that model behaviors observed in drug addicts. Traditionally, self-administration schedules were designed to independently study changes in drug-taking behaviors (e.g., rate of responding, reinforcing efficacy, etc.). The threshold self-administration procedure was developed to measure two distinct dependent measures within the same experimental session that are important in the study of drug addiction: the maximal price an animal expends to self-administer cocaine and an animal's preferred level of cocaine consumption when available at a low behavioral cost.
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Affiliation(s)
- Erik B Oleson
- Department of Neurobiology and Anatomy, University of Maryland, School of Medicine, Baltimore, MD, USA
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Oleson EB, Richardson JM, Roberts DCS. A novel IV cocaine self-administration procedure in rats: differential effects of dopamine, serotonin, and GABA drug pre-treatments on cocaine consumption and maximal price paid. Psychopharmacology (Berl) 2011; 214:567-77. [PMID: 21110008 PMCID: PMC3289955 DOI: 10.1007/s00213-010-2058-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 10/14/2010] [Indexed: 11/26/2022]
Abstract
RATIONALE Behavior occurring during cocaine self-administration can be classified as either consummatory or appetitive. These two concepts are usually addressed independently using separate reinforcement schedules. For example, appetitive behavior can be assessed with a progressive ratio schedule, whereas consummatory behavior is typically measured using a fixed ratio schedule. OBJECTIVES Depending on the schedule used, it is often difficult to determine whether a particular drug pretreatment is affecting self-administration through an effect on appetitive responding, consummatory responding, or perhaps both. In the present study, we tested the effect of pretreating rats with four different drugs on appetitive and consummatory behaviors. MATERIALS AND METHODS We recently developed a technique that provides an independent assessment of both behavioral concepts within the same experimental session. In this threshold procedure, rats are offered a descending series of 11 unit doses (422-1.3 μg/injection) during consecutive timed intervals under a fixed-ratio schedule. Consummatory behavior can be analyzed by assessing intake at high unit doses; an estimate of appetitive responding can be determined from responding occurring at the threshold dose. Applying behavioral economics to these data provides dependent measures of consumption when minimally constrained by price and the maximal price paid (P (max)) for cocaine. RESULTS Haloperidol increased cocaine consumption when minimally constrained by price but decreased P (max). In contrast, D: -amphetamine increased P (max). Fluoxetine decreased P (max) and consumption when minimally constrained by price. Baclofen selectively decreased P (max). CONCLUSIONS These data suggest that drug pretreatments can alter consummatory and appetitive behavior differently because each concept involves distinct neural mechanisms.
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Affiliation(s)
- Erik B Oleson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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España RA, Oleson EB, Locke JL, Brookshire BR, Roberts DCS, Jones SR. The hypocretin-orexin system regulates cocaine self-administration via actions on the mesolimbic dopamine system. Eur J Neurosci 2009; 31:336-48. [PMID: 20039943 DOI: 10.1111/j.1460-9568.2009.07065.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent evidence suggests that the hypocretin-orexin system participates in the regulation of reinforcement processes. The current studies examined the extent to which hypocretin neurotransmission regulates behavioral and neurochemical responses to cocaine, and behavioral responses to food reinforcement. These studies used a combination of fixed ratio, discrete trials, progressive ratio and threshold self-administration procedures to assess whether the hypocretin 1 receptor antagonist, SB-334867, reduces cocaine self-administration in rats. Progressive ratio sucrose self-administration procedures were also used to assess the extent to which SB-334867 reduces responding to a natural reinforcer in food-restricted and food-sated rats. Additionally, these studies used microdialysis and in vivo voltammetry in rats to examine whether SB-334867 attenuates the effects of cocaine on dopamine signaling within the nucleus accumbens core. Furthermore, in vitro voltammetry was used to examine whether hypocretin knockout mice display attenuated dopamine responses to cocaine. Results indicate that when SB-334867 was administered peripherally or within the ventral tegmental area, it reduced the motivation to self-administer cocaine and attenuated cocaine-induced enhancement of dopamine signaling. SB-334867 also reduced the motivation to self-administer sucrose in food-sated but not food-restricted rats. Finally, hypocretin knockout mice displayed altered baseline dopamine signaling and reduced dopamine responses to cocaine. Combined, these studies suggest that hypocretin neurotransmission participates in reinforcement processes, likely through modulation of the mesolimbic dopamine system. Additionally, the current observations suggest that the hypocretin system may provide a target for pharmacotherapies to treat cocaine addiction.
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Affiliation(s)
- Rodrigo A España
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
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Abstract
The present study was designed to reveal the relationship between cocaine-induced dopamine uptake changes and patterns of cocaine self-administration observed under a fixed-ratio schedule. Cocaine was intravenously infused into anesthetized rats, according to inter-infusion intervals obtained from self-administering animals, and dopamine uptake changes (apparent K(m)) were assessed in the nucleus accumbens using voltammetry. The data demonstrate that cocaine-induced dopamine transporter (DAT) inhibition accounts for the accumbal dopamine fluctuations, which are associated with the cyclic regularity of cocaine intake observed during self-administration. Specifically, the inter-infusion intervals that are maintained during cocaine self-administration correlate with the maintenance of a rapidly changing level of dopamine uptake inhibition, which appears to be tightly regulated. Furthermore, this maintained level of dopamine uptake inhibition was found to shift upward using intervals from animals that had shown an escalation in the rate of cocaine self-administration. Although no significant change in the apparent K(m) was revealed in animals that exhibited an escalation in the rate of cocaine intake, an increased dopamine uptake rate was found suggesting an upregulation of DAT number in response to a history of high cocaine intake. This is the first demonstration of the tight correlation that exists between the level of dopamine uptake inhibition and rates of cocaine self-administration. Moreover, a new mathematical model was created that quantitatively describes the changes in cocaine-induced dopamine uptake and correctly predicts the level of dopamine uptake inhibition. This model permits a computational interpretation of cocaine-induced dopamine uptake changes during cocaine self-administration.
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Affiliation(s)
- Erik B. Oleson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine
| | - Sanjay Talluri
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina
| | - Steven R. Childers
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine
| | - James E. Smith
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine
| | - David C. S. Roberts
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine
| | - Keith D. Bonin
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina
| | - Evgeny A. Budygin
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine
,Corresponding Author: Evgeny A. Budygin, Ph.D., Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, Tel: (336) 716-8530, Fax: (336) 716-8501
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Morgan D, Liu Y, Oleson EB, Roberts DCS. Cocaine self-administration on a hold-down schedule of reinforcement in rats. Psychopharmacology (Berl) 2009; 201:601-9. [PMID: 18797847 DOI: 10.1007/s00213-008-1328-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Accepted: 08/30/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVE Although many contingencies operating in the natural environment include continuous dimensions of responses and reinforcers, previous studies of drug self-administration have almost exclusively used discrete dimensions of responses (e.g., a lever press) and reinforcers (e.g., 1.0 mg/kg/injection cocaine). Therefore, the present study provides an initial examination under experimental conditions with both responses and reinforcers measured along continuous dimensions. MATERIALS AND METHODS Cocaine-maintained responding was studied in rats under a novel, hold-down schedule of reinforcement wherein the duration of the response was directly related to the magnitude of the reinforcer. These conditions were established by activating the syringe pump when the lever was pressed down and turning the pump off when the lever was released. The concentration of cocaine available in the syringe was varied across sessions. RESULTS Cocaine self-administration was readily maintained under these conditions and remained stable across sessions. Responding was concentration dependent, with the number of responses and total duration of the response inversely related to concentration, and overall session intake of cocaine was stable across concentrations. In general, the duration of the responses were less than 0.5 s and did not vary as a function of concentration. CONCLUSIONS Stability of responding under these schedule conditions was acquired quickly. This schedule of reinforcement may be useful for comparing across drug classes, can be extended for use with other types of responses and reinforcers, and may be more representative of the natural world where response-reinforcer contingencies are more likely to be experienced along continuous, rather than discrete, dimensions.
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Affiliation(s)
- Drake Morgan
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
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Budygin EA, Oleson EB, Mathews TA, Läck AK, Diaz MR, McCool BA, Jones SR. Effects of chronic alcohol exposure on dopamine uptake in rat nucleus accumbens and caudate putamen. Psychopharmacology (Berl) 2007; 193:495-501. [PMID: 17492432 DOI: 10.1007/s00213-007-0812-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 04/21/2007] [Indexed: 11/25/2022]
Abstract
RATIONALE Existing data strongly suggest that alcohol affects dopamine (DA) neurotransmission in the brain. However, many questions remain about the effects of alcohol on the delicate equilibrium between such neurochemical processes as DA release and uptake. Dysregulation of these processes in the mesolimbic and nigrostriatal systems after chronic alcohol ingestion could be a neuroadaptation contributing to dependence. OBJECTIVES In the present study, we have employed an alcohol vapor inhalation model to characterize the effects of chronic alcohol exposure on DA dynamics in rat nucleus accumbens (NAc) and caudate putamen (CP) using fast-scan cyclic voltammetry (FSCV) in brain slices. This method provides a unique view of real-time, spatially resolved changes in DA concentration. RESULTS We found that chronic alcohol exposure enhanced DA uptake rates in rat NAc and CP. These changes would have the effect of down-regulating extracellular DA levels, presumably a compensatory effect related to increased DA release by repeated alcohol exposure. The sensitivity of terminal release-regulating DA autoreceptors was not different in alcohol-exposed rats compared with alcohol-naïve animals. CONCLUSIONS The DA uptake changes after chronic alcohol exposure documented here using FSCV may be associated with a compensatory response of the DA system aimed at decreasing DA signaling. Alterations in autoreceptor function may require relatively long lasting alcohol exposure.
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Affiliation(s)
- Evgeny A Budygin
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA.
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Lominac KD, Oleson EB, Pava M, Klugmann M, Schwarz MK, Seeburg PH, During MJ, Worley PF, Kalivas PW, Szumlinski KK. Distinct roles for different Homer1 isoforms in behaviors and associated prefrontal cortex function. J Neurosci 2006; 25:11586-94. [PMID: 16354916 PMCID: PMC6726036 DOI: 10.1523/jneurosci.3764-05.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Homer1 mutant mice exhibit behavioral and neurochemical abnormalities that are consistent with an animal model of schizophrenia. Because the Homer1 gene encodes both immediate early gene (IEG) and constitutively expressed (CC) gene products, we used the local infusion of adeno-associated viral vectors carrying different Homer1 transcriptional variants into the prefrontal cortex (PFC) to distinguish between the roles for IEG and CC Homer1 isoforms in the "schizophrenia-like" phenotype of Homer1 mutant mice. PFC overexpression of the IEG Homer1 isoform Homer1a reversed the genotypic differences in behavioral adaptation to repeated stress, whereas overexpression of the constitutively expressed Homer1 isoform Homer1c reversed the genotypic differences in sensorimotor and cognitive processing, as well as cocaine behavioral sensitivity. Homer1a overexpression did not influence PFC basal glutamate content but blunted the glutamate response to cocaine in wild-type mice. In contrast, Homer1c overexpression reversed the genotypic difference in PFC basal glutamate content and enhanced cocaine-induced elevations in glutamate. These data demonstrate active and distinct roles for Homer1a and Homer1c isoforms in the PFC in the mediation of behavior, in the maintenance of basal extracellular glutamate, and in the regulation of PFC glutamate release relevant to schizophrenia and stimulant abuse comorbidity.
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Affiliation(s)
- Kevin D Lominac
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Szumlinski KK, Abernathy KE, Oleson EB, Klugmann M, Lominac KD, He DY, Ron D, During M, Kalivas PW. Homer isoforms differentially regulate cocaine-induced neuroplasticity. Neuropsychopharmacology 2006; 31:768-77. [PMID: 16160706 DOI: 10.1038/sj.npp.1300890] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Homer proteins modulate neuroplasticity in excitatory synapses and are dynamically regulated by cocaine. Whereas acute cocaine elevates immediate-early gene (short) isoforms of Homer1 in the nucleus accumbens, withdrawal from repeated cocaine administration downregulates the expression of constitutive Homer1 isoforms. The present study determined whether or not this downregulation in constitutive Homer expression in the accumbens is necessary for enduring alterations in cocaine-induced changes in the brain and behavior. The long vs short Homer isoforms were overexpressed in the rat nucleus accumbens during drug abstinence, and the adaptations elicited by repeated cocaine on glutamate transmission and motor behavior were measured. It was found that both chronic and acute overexpression of constitutive, but not short, Homer isoforms abolished cocaine-induced sensitization of locomotor hyperactivity and prevented the development of glutamate abnormalities in the accumbens, including the reduction in basal extracellular glutamate content and the sensitized glutamate response to a subsequent cocaine challenge injection. Together, these data indicate that the enduring reduction of long Homer isoforms in the nucleus accumbens of cocaine-withdrawn rats is necessary for the expression of cocaine-induced neuroplasticity.
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Affiliation(s)
- Karen K Szumlinski
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA.
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Szumlinski KK, Lominac KD, Oleson EB, Walker JK, Mason A, Dehoff MH, Klugmann M, Klugman M, Cagle S, Welt K, During M, Worley PF, Middaugh LD, Kalivas PW. Homer2 is necessary for EtOH-induced neuroplasticity. J Neurosci 2006; 25:7054-61. [PMID: 16049182 PMCID: PMC6724845 DOI: 10.1523/jneurosci.1529-05.2005] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Homer proteins are integral to the assembly of proteins regulating glutamate signaling and synaptic plasticity. Constitutive Homer2 gene deletion [knock-out (KO)] and rescue with adeno-associated viral (AAV) transfection of Homer2b was used to demonstrate the importance of Homer proteins in neuroplasticity produced by repeated ethanol (EtOH) administration. Homer2 KO mice avoided drinking high concentrations of EtOH and did not develop place preference or locomotor sensitization after repeated EtOH administration. The deficient behavioral plasticity to EtOH after Homer2 deletion was paralleled by a lack of augmentation in the rise in extracellular dopamine and glutamate elicited by repeated EtOH injections. The genotypic differences in EtOH-induced change in behavior and neurochemistry were essentially reversed by AAV-mediated transfection of Homer2b into accumbens cells including, differences in EtOH preference, locomotor sensitization, and EtOH-induced elevations in extracellular glutamate and dopamine. These data demonstrate a necessary and active role for accumbens Homer2 expression in regulating EtOH-induced behavioral and cellular neuroplasticity.
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Affiliation(s)
- Karen K Szumlinski
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Szumlinski KK, Lominac KD, Kleschen MJ, Oleson EB, Dehoff MH, Schwarz MK, Schwartz MK, Seeburg PH, Seeberg PH, Worley PF, Kalivas PW. Behavioral and neurochemical phenotyping of Homer1 mutant mice: possible relevance to schizophrenia. Genes Brain Behav 2005; 4:273-88. [PMID: 16011574 DOI: 10.1111/j.1601-183x.2005.00120.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Homer proteins are involved in the functional assembly of postsynaptic density proteins at glutamatergic synapses and are implicated in learning, memory and drug addiction. Here, we report that Homer1-knockout (Homer1-KO) mice exhibit behavioral and neurochemical abnormalities that are consistent with the animal models of schizophrenia. Relative to wild-type mice, Homer1-KO mice exhibited deficits in radial arm maze performance, impaired prepulse inhibition, enhanced 'behavioral despair', increased anxiety in a novel objects test, enhanced reactivity to novel environments, decreased instrumental responding for sucrose and enhanced MK-801- and methamphetamine-stimulated motor behavior. No-net-flux in vivo microdialysis revealed a decrease in extracellular glutamate content in the nucleus accumbens and an increase in the prefrontal cortex. Moreover, in Homer1-KO mice, cocaine did not stimulate a rise in frontal cortex extracellular glutamate levels, suggesting hypofrontality. These behavioral and neurochemical data derived from Homer1 mutant mice are consistent with the recent association of schizophrenia with a single-nucleotide polymorphism in the Homer1 gene and suggest that the regulation of extracellular levels of glutamate within limbo-corticostriatal structures by Homer1 gene products may be involved in the pathogenesis of this neuropsychiatric disorder.
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Affiliation(s)
- K K Szumlinski
- Department of Physiology and Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
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