1
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Smith AC, Ghoshal S, Centanni SW, Heyer MP, Corona A, Wills L, Andraka E, Lei Y, O’Connor RM, Caligiuri SP, Khan S, Beaumont K, Sebra RP, Kieffer BL, Winder DG, Ishikawa M, Kenny PJ. A master regulator of opioid reward in the ventral prefrontal cortex. Science 2024; 384:eadn0886. [PMID: 38843332 PMCID: PMC11323237 DOI: 10.1126/science.adn0886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 04/17/2024] [Indexed: 06/16/2024]
Abstract
In addition to their intrinsic rewarding properties, opioids can also evoke aversive reactions that protect against misuse. Cellular mechanisms that govern the interplay between opioid reward and aversion are poorly understood. We used whole-brain activity mapping in mice to show that neurons in the dorsal peduncular nucleus (DPn) are highly responsive to the opioid oxycodone. Connectomic profiling revealed that DPn neurons innervate the parabrachial nucleus (PBn). Spatial and single-nuclei transcriptomics resolved a population of PBn-projecting pyramidal neurons in the DPn that express μ-opioid receptors (μORs). Disrupting μOR signaling in the DPn switched oxycodone from rewarding to aversive and exacerbated the severity of opioid withdrawal. These findings identify the DPn as a key substrate for the abuse liability of opioids.
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Affiliation(s)
- Alexander C.W. Smith
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
- Present address: Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Soham Ghoshal
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Samuel W. Centanni
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Mary P. Heyer
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Alberto Corona
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Lauren Wills
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Emma Andraka
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Ye Lei
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Richard M. O’Connor
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Stephanie P.B. Caligiuri
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Sohail Khan
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Kristin Beaumont
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Robert P. Sebra
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Brigitte L. Kieffer
- Douglas Research Center, Department of Psychiatry, McGill University, Montréal, Quebec, Canada, and INSERM U1114, Department of Psychiatry, University of Strasbourg, Strasbourg, France
| | - Danny G. Winder
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Masago Ishikawa
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
| | - Paul J. Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York 10029, USA
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2
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Estave PM, Albertson SE, Karkhanis AN, Jones SR. Co-targeting the kappa opioid receptor and dopamine transporter reduces motivation to self-administer cocaine and partially reverses dopamine system dysregulation. Sci Rep 2024; 14:6509. [PMID: 38499566 PMCID: PMC10948819 DOI: 10.1038/s41598-024-53463-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/31/2024] [Indexed: 03/20/2024] Open
Abstract
Cocaine disrupts dopamine (DA) and kappa opioid receptor (KOR) system activity, with long-term exposure reducing inhibiton of DA uptake by cocaine and increasing KOR system function. Single treatment therapies have not been successful for cocaine use disorder; therefore, this study focuses on a combination therapy targeting the dopamine transporter (DAT) and KOR. Sprague Dawley rats self-administered 5 days of cocaine (1.5 mg/kg/inf, max 40 inf/day, FR1), followed by 14 days on a progressive ratio (PR) schedule (0.19 mg/kg/infusion). Behavioral effects of individual and combined administration of phenmetrazine and nBNI were then examined using PR. Additionally, ex vivo fast scan cyclic voltammetry was then used to assess alterations in DA and KOR system activity in the nucleus accumbens before and after treatments. Chronic administration of phenmetrazine as well as the combination of phenmetrazine and nBNI-but not nBNI alone-significantly reduced PR breakpoints. In addition, the combination of phenmetrazine and nBNI partially reversed cocaine-induced neurodysregulations of the KOR and DA systems, indicating therapeutic benefits of targeting the DA and KOR systems in tandem. These data highlight the potential benefits of the DAT and KOR as dual-cellular targets to reduce motivation to administer cocaine and reverse cocaine-induced alterations of the DA system.
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Affiliation(s)
- Paige M Estave
- Department of Physiology and Pharmacology, Wake University Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC, 27157, USA
| | - Steven E Albertson
- Department of Physiology and Pharmacology, Wake University Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC, 27157, USA
| | - Anushree N Karkhanis
- Department of Psychology, Binghamton University - State University of New York, Binghamton, NY, 13902, USA
| | - Sara R Jones
- Department of Physiology and Pharmacology, Wake University Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC, 27157, USA.
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3
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Dawes MH, Estave PM, Albertson SE, Wallace CW, Holleran KM, Jones SR. Nicotine modifies cocaine responding in a concurrent self-administration model. Drug Alcohol Depend 2023; 251:110960. [PMID: 37703771 PMCID: PMC10710190 DOI: 10.1016/j.drugalcdep.2023.110960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 09/15/2023]
Abstract
BACKGROUND Preclinical models of cocaine use disorder (CUD) have not yielded any FDA-approved pharmacotherapies, potentially due to a focus on cocaine use in isolation, which may not fully translate to real-world drug taking patterns. Cocaine and nicotine are commonly used together, and clinical research suggests that nicotine may increase the potency and reinforcing strength of cocaine. In this study, we sought to determine whether and how the addition of nicotine would alter ongoing intravenous cocaine self-administration and motivation to take cocaine in rats. METHODS Male Sprague-Dawley rats self-administered cocaine alone on a long access, Fixed Ratio one (FR1) schedule, and then switched to a combination of cocaine and nicotine. Finally, rats responded on a Progressive Ratio (PR) schedule for several doses of cocaine alone and in combination with a single dose of nicotine. RESULTS Under long access conditions, rats co-self-administering cocaine and nicotine responded less and with decreased response rates than for cocaine alone and did not escalate responding. However, under PR conditions that test motivation to take drugs, the dose response curve for the combination was shifted upwards relative to cocaine alone. CONCLUSIONS Together, these results suggest that nicotine may enhance the reinforcing strength of cocaine, increasing PR responding for cocaine across the dose response curve.
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Affiliation(s)
- Monica H Dawes
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States
| | - Paige M Estave
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States; Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States
| | - Steven E Albertson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States
| | - Conner W Wallace
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States
| | - Katherine M Holleran
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States
| | - Sara R Jones
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27101, United States.
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Urena ES, Diezel CC, Serna M, Hala'ufia G, Majuta L, Barber KR, Vanderah TW, Riegel AC. K v 7 Channel Opener Retigabine Reduces Self-Administration of Cocaine but Not Sucrose in Rats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.18.541208. [PMID: 37292619 PMCID: PMC10245780 DOI: 10.1101/2023.05.18.541208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The increasing rates of drug misuse highlight the urgency of identifying improved therapeutics for treatment. Most drug-seeking behaviors that can be modeled in rodents utilize the repeated intravenous self-administration (SA) of drugs. Recent studies examining the mesolimbic pathway suggest that K v 7/KCNQ channels may contribute in the transition from recreational to chronic drug use. However, to date, all such studies used noncontingent, experimenter-delivered drug model systems, and the extent to which this effect generalizes to rats trained to self-administer drug is not known. Here, we tested the ability of retigabine (ezogabine), a K v 7 channel opener, to regulate instrumental behavior in male Sprague Dawley rats. We first validated the ability of retigabine to target experimenter-delivered cocaine in a CPP assay and found that retigabine reduced the acquisition of place preference. Next, we trained rats for cocaine-SA under a fixed-ratio or progressive-ratio reinforcement schedule and found that retigabine-pretreatment attenuated the self-administration of low to moderate doses of cocaine. This was not observed in parallel experiments, with rats self-administering sucrose, a natural reward. Compared to sucrose-SA, cocaine-SA was associated with reductions in the expression of the K v 7.5 subunit in the nucleus accumbens, without alterations in K v 7.2 and K v 7.3. Therefore, these studies reveal a reward specific reduction in SA behavior considered relevant for the study of long-term compulsive-like behavior and supports the notion that K v 7 is a potential therapeutic target for human psychiatric diseases with dysfunctional reward circuitry.
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5
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Downs AM, McElligott ZA. Noradrenergic circuits and signaling in substance use disorders. Neuropharmacology 2022; 208:108997. [PMID: 35176286 PMCID: PMC9498225 DOI: 10.1016/j.neuropharm.2022.108997] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 01/06/2022] [Accepted: 02/08/2022] [Indexed: 12/20/2022]
Abstract
The central noradrenergic system innervates almost all regions of the brain and, as such, is well positioned to modulate many neural circuits implicated in behaviors and physiology underlying substance use disorders. Ample pharmacological evidence demonstrates that α1, α2, and β adrenergic receptors may serve as therapeutic targets to reduce drug -seeking behavior and drug withdrawal symptoms. Further, norepinephrine is a key modulator of the stress response, and stress has been heavily implicated in reinstatement of drug taking. In this review, we discuss recent advances in our understanding of noradrenergic circuitry and noradrenergic receptor signaling in the context of opioid, alcohol, and psychostimulant use disorders.
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Affiliation(s)
- Anthony M Downs
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| | - Zoe A McElligott
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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6
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Kohno M, Dennis LE, McCready H, Hoffman WF. Dopamine dysfunction in stimulant use disorders: mechanistic comparisons and implications for treatment. Mol Psychiatry 2022; 27:220-229. [PMID: 34117366 PMCID: PMC8664889 DOI: 10.1038/s41380-021-01180-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/13/2021] [Accepted: 05/26/2021] [Indexed: 12/14/2022]
Abstract
Dopamine system deficiencies and associated behavioral phenotypes may be a critical barrier to success in treating stimulant use disorders. Similarities in dopamine dysfunction between cocaine and methamphetamine use disorder but also key differences may impact treatment efficacy and outcome. This review will first compare the epidemiology of cocaine and methamphetamine use disorder. A detailed account of the pharmacokinetic and pharmacodynamic properties associated with each drug will then be discussed, with an emphasis on effects on the dopamine system and associated signaling pathways. Lastly, treatment results from pharmacological clinical trials will be summarized along with a more comprehensive review of the involvement of the trace amine-associated receptor on dopamine signaling dysfunction among stimulants and its potential as a therapeutic target.
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Affiliation(s)
- Milky Kohno
- Department of Psychiatry, Oregon Health & Science University, Portland, OR, USA. .,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA. .,Research and Development Service, Veterans Affairs Portland Health Care System, Portland, OR, USA. .,Methamphetamine Abuse Research Center, Oregon Health & Science University and Veterans Affairs Portland Health Care System, Portland, OR, USA.
| | - Laura E. Dennis
- Department of Psychiatry, Oregon Health & Science University, Portland, Oregon, USA,Research & Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon, USA
| | - Holly McCready
- Department of Psychiatry, Oregon Health & Science University, Portland, Oregon, USA,Research & Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon, USA
| | - William F. Hoffman
- Department of Psychiatry, Oregon Health & Science University, Portland, Oregon, USA,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, USA,Research & Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon, USA,Mental Health Division, Veterans Affairs Portland Health Care System, Portland, Oregon, USA,Methamphetamine Abuse Research Center, Oregon Health & Science University and Veterans Affairs Portland Health Care System, Portland, Oregon, USA
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7
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Effects of neonatal dopaminergic lesion on oral cocaine self-administration in rats: Higher female vulnerability to cocaine consumption. Pharmacol Biochem Behav 2021; 212:173315. [PMID: 34942237 DOI: 10.1016/j.pbb.2021.173315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 12/12/2021] [Accepted: 12/13/2021] [Indexed: 11/22/2022]
Abstract
The dopaminergic system is associated with cocaine-seeking behaviors, being influenced by other neurotransmitters such as GABA and deregulated by chronic cocaine self-administration. Administration of 6-hydroxydopamine (6-OHDA) to neonatal rats produces a depletion of brain dopamine, mainly, that results in behavioral alterations in adulthood. This model can be applied to better understanding of the role of the dopaminergic system in cocaine use and how its behavioral effects can modulate drug intake. Though there are well-established sex differences in the pattern of drug use, there are no published studies investigating sex-dependent effects of neonatal lesions with 6-OHDA on cocaine self-administration nor regarding GABAA receptor (GABAAR) subunits expression. Herein, neurotoxic lesion was induced in male and female neonatal rats by intracisternal injection of 6-OHDA at PND 4, and locomotion was evaluated before and after cocaine self-administration. Cocaine was diluted in a sweet solution (sucrose 1.5%) and offered for 27 consecutive 3-h daily sessions via a dispenser for oral intake, in an operant chamber under a fixed-ratio 1 (FR1) schedule. The 6-OHDA lesion reduced oral cocaine self-administration in male and female rats. Female rats, independent of dopaminergic condition, consumed more cocaine-containing solution than sucrose-only solution. Furthermore, as expected, 6-OHDA-lesioned animals presented a higher basal locomotor activity when compared to sham rats. We evaluated GABAAR subunit expression and found no statistically significant differences between rats that self-administered a sucrose-only solution and those that self-administered a cocaine-containing solution. Even when the reward system is depleted, some behavioral differences remain in females, providing more data that highlight the female vulnerability to cocaine consumption.
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8
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Abstract
Addictive drugs are habit-forming. Addiction is a learned behavior; repeated exposure to addictive drugs can stamp in learning. Dopamine-depleted or dopamine-deleted animals have only unlearned reflexes; they lack learned seeking and learned avoidance. Burst-firing of dopamine neurons enables learning-long-term potentiation (LTP)-of search and avoidance responses. It sets the stage for learning that occurs between glutamatergic sensory inputs and GABAergic motor-related outputs of the striatum; this learning establishes the ability to search and avoid. Independent of burst-firing, the rate of single-spiking-or "pacemaker firing"-of dopaminergic neurons mediates motivational arousal. Motivational arousal increases during need states and its level determines the responsiveness of the animal to established predictive stimuli. Addictive drugs, while usually not serving as an external stimulus, have varying abilities to activate the dopamine system; the comparative abilities of different addictive drugs to facilitate LTP is something that might be studied in the future.
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Affiliation(s)
- Roy A Wise
- Intramural Research Program, National Institute on Drug Abuse, 250 Mason Lord Drive, Baltimore, MD, USA.
- Behavior Genetics Laboratory, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA.
| | - Chloe J Jordan
- Division of Alcohol, Drugs and Addiction, Department of Psychiatry, Harvard Medical School, McLean Hospital, 115 Mill Street, Belmont, MA, 02478, USA
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9
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Abstract
Drug addiction is a chronic relapsing disorder, and a significant amount of research has been devoted to understand the factors that contribute to the development, loss of control, and persistence of compulsive addictive behaviors. In this review, we provide an overview of various theories of addiction to drugs of abuse and the neurobiology involved in elements of the addiction cycle. Specific focus is devoted to the role of the mesolimbic pathway in acute drug reinforcement and occasional drug use, the role of the mesocortical pathway and associated areas (e.g., the dorsal striatum) in escalation/dependence, and the contribution of these pathways and associated circuits to conditioned responses, drug craving, and loss of behavioral control that may underlie drug relapse. By enhancing the understanding of the neurobiological factors that mediate drug addiction, continued preclinical and clinical research will aid in the development of novel therapeutic interventions that can serve as effective long-term treatment strategies for drug-dependent individuals.
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Affiliation(s)
- Matthew W Feltenstein
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | - Ronald E See
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA
- Department of Psychology, Westmont College, Santa Barbara, California 93108, USA
| | - Rita A Fuchs
- Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington 99164-7620, USA
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10
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Shifting motivational states: The effects of nucleus accumbens dopamine and opioid receptor activation on a modified effort-based choice task. Behav Brain Res 2020; 399:112999. [PMID: 33161034 DOI: 10.1016/j.bbr.2020.112999] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/14/2020] [Accepted: 10/30/2020] [Indexed: 01/26/2023]
Abstract
The nucleus accumbens (NAc) is critical for regulating the appetitive and consummatory phases of motivated behavior. These experiments examined the effects of dopamine and opioid receptor manipulations within the NAc during an effort-based choice task that allowed for simultaneous assessment of both phases of motivation. Male Sprague-Dawley rats received bilateral guide cannulas targeting the NAc core and were tested in 1-hr sessions with free access to rat chow and the choice to work for sugar pellets on a progressive ratio 2 (PR2) reinforcement schedule. Individual groups of rats were tested following stimulation or blockade of NAc D1-like or D2-like receptors, stimulation of μ-, δ-, or κ-opioid receptors, or antagonism of opioid receptors. Behavior was examined under ad libitum conditions and following 23-h food restriction. NAc blockade of the D1-like receptors or stimulation of the D2 receptor reduced break point for earning sugar pellets; D2 receptor stimulation also modestly lowered chow intake. NAc μ-opioid receptor stimulation increased intake of the freely-available chow while simultaneously reducing break point for the sugar pellets. In non-restricted conditions, δ-opioid receptor stimulation increased both food intake and breakpoint. There were no effects of stimulating NAc D1 or κ receptors, nor did blocking D2 or opioid receptors affect task behavior. These data support prior literature linking dopamine to appetitive motivational processes, and suggest that μ- and δ-opioid receptors affect food-directed motivation differentially. Specifically, μ-opioid receptors shifted behavior towards consumption, and δ-opioid receptor enhanced both sugar-seeking and consumption of the pabulum chow when animals were not food restricted.
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11
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Abstract
Addiction is commonly identified with habitual nonmedical self-administration of drugs. It is usually defined by characteristics of intoxication or by characteristics of withdrawal symptoms. Such addictions can also be defined in terms of the brain mechanisms they activate; most addictive drugs cause elevations in extracellular levels of the neurotransmitter dopamine. Animals unable to synthesize or use dopamine lack the conditioned reflexes discussed by Pavlov or the appetitive behavior discussed by Craig; they have only unconditioned consummatory reflexes. Burst discharges (phasic firing) of dopamine-containing neurons are necessary to establish long-term memories associating predictive stimuli with rewards and punishers. Independent discharges of dopamine neurons (tonic or pacemaker firing) determine the motivation to respond to such cues. As a result of habitual intake of addictive drugs, dopamine receptors expressed in the brain are decreased, thereby reducing interest in activities not already stamped in by habitual rewards.
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Affiliation(s)
- Roy A Wise
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA; .,Behavioral Genetics Laboratory, McLean Hospital, Belmont, Massachusetts 02478, USA;
| | - Mykel A Robble
- Behavioral Genetics Laboratory, McLean Hospital, Belmont, Massachusetts 02478, USA;
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12
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Chemogenetic Manipulation of Dopamine Neurons Dictates Cocaine Potency at Distal Dopamine Transporters. J Neurosci 2020; 40:8767-8779. [PMID: 33046544 DOI: 10.1523/jneurosci.0894-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/18/2020] [Accepted: 09/27/2020] [Indexed: 12/21/2022] Open
Abstract
The reinforcing efficacy of cocaine is largely determined by its capacity to inhibit the dopamine transporter (DAT), and emerging evidence suggests that differences in cocaine potency are linked to several symptoms of cocaine use disorder. Despite this evidence, the neural processes that govern cocaine potency in vivo remain unclear. In male rats, we used chemogenetics with intra-VTA microinfusions of the agonist clozapine-n-oxide to bidirectionally modulate dopamine neurons. Using ex vivo fast scan cyclic voltammetry, pharmacological probes of the DAT, biochemical assessments of DAT membrane availability and phosphorylation, and cocaine self-administration, we tested the effects of chemogenetic manipulations on cocaine potency at distal DATs in the nucleus accumbens as well as the behavioral economics of cocaine self-administration. We discovered that chemogenetic manipulation of dopamine neurons produced rapid, bidirectional modulation of cocaine potency at DATs in the nucleus accumbens. We then provided evidence that changes in cocaine potency are associated with alterations in DAT affinity for cocaine and demonstrated that this change in affinity coincides with DAT conformation biases and changes in DAT phosphorylation state. Finally, we showed that chemogenetic manipulation of dopamine neurons alters cocaine consumption in a manner consistent with changes in cocaine potency at distal DATs. Based on the spatial and temporal constraints inherent to our experimental design, we posit that changes in cocaine potency are driven by alterations in dopamine neuron activity. When considered together, these observations provide a novel mechanism through which GPCRs regulate cocaine's pharmacological and behavioral effects.SIGNIFICANCE STATEMENT Differences in the pharmacological effects of cocaine are believed to influence the development and progression of cocaine use disorder. However, the biological and physiological processes that determine sensitivity to cocaine remain unclear. In this work, we use a combination of chemogenetics, fast scan cyclic voltammetry, pharmacology, biochemistry, and cocaine self-administration with economic demand analysis to demonstrate a novel mechanism by which cocaine potency is determined in vivo These studies identify a novel process by which the pharmacodynamics of cocaine are derived in vivo, and thus this work has widespread implications for understanding the mechanisms that regulate cocaine consumption across stages of addiction.
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13
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Buck SA, Torregrossa MM, Logan RW, Freyberg Z. Roles of dopamine and glutamate co-release in the nucleus accumbens in mediating the actions of drugs of abuse. FEBS J 2020; 288:1462-1474. [PMID: 32702182 DOI: 10.1111/febs.15496] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/30/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022]
Abstract
Projections of ventral tegmental area dopamine (DA) neurons to the medial shell of the nucleus accumbens have been increasingly implicated as integral to the behavioral and physiological changes involved in the development of substance use disorders (SUDs). Recently, many of these nucleus accumbens-projecting DA neurons were found to also release the neurotransmitter glutamate. This glutamate co-release from DA neurons is critical in mediating the effect of drugs of abuse on addiction-related behaviors. Potential mechanisms underlying the role(s) of dopamine/glutamate co-release in contributing to SUDs are unclear. Nevertheless, an important clue may relate to glutamate's ability to potentiate loading of DA into synaptic vesicles within terminals in the nucleus accumbens in response to drug-induced elevations in neuronal activity, enabling a more robust release of DA after stimulation. Here, we summarize how drugs of abuse, particularly cocaine, opioids, and alcohol, alter DA release in the nucleus accumbens medial shell, examine the potential role of DA/glutamate co-release in mediating these effects, and discuss future directions for further investigating these mechanisms.
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Affiliation(s)
- Silas A Buck
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Psychiatry, Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mary M Torregrossa
- Department of Psychiatry, Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ryan W Logan
- Department of Psychiatry, Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA.,Center for Systems Neurogenetics of Addiction, The Jackson Laboratory, Bar Harbor, ME, USA
| | - Zachary Freyberg
- Department of Psychiatry, Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
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14
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Nolan SO, Zachry JE, Johnson AR, Brady LJ, Siciliano CA, Calipari ES. Direct dopamine terminal regulation by local striatal microcircuitry. J Neurochem 2020; 155:475-493. [PMID: 32356315 DOI: 10.1111/jnc.15034] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 02/06/2023]
Abstract
Regulation of axonal dopamine release by local microcircuitry is at the hub of several biological processes that govern the timing and magnitude of signaling events in reward-related brain regions. An important characteristic of dopamine release from axon terminals in the striatum is that it is rapidly modulated by local regulatory mechanisms. These processes can occur via homosynaptic mechanisms-such as presynaptic dopamine autoreceptors and dopamine transporters - as well heterosynaptic mechanisms such as retrograde signaling from postsynaptic cholinergic and dynorphin systems, among others. Additionally, modulation of dopamine release via diffusible messengers, such as nitric oxide and hydrogen peroxide, allows for various metabolic factors to quickly and efficiently regulate dopamine release and subsequent signaling. Here we review how these mechanisms work in concert to influence the timing and magnitude of striatal dopamine signaling, independent of action potential activity at the level of dopaminergic cell bodies in the midbrain, thereby providing a parallel pathway by which dopamine can be modulated. Understanding the complexities of local regulation of dopamine signaling is required for building comprehensive frameworks of how activity throughout the dopamine system is integrated to drive signaling and control behavior.
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Affiliation(s)
- Suzanne O Nolan
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Jennifer E Zachry
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Amy R Johnson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Lillian J Brady
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA.,Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN TN, USA
| | - Erin S Calipari
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA.,Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN TN, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.,Department of Psychiatry and Behavioral Sciences, Vanderbilt University, Nashville, TN, USA
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15
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Coutens B, Mouledous L, Stella M, Rampon C, Lapeyre-Mestre M, Roussin A, Guiard BP, Jouanjus E. Lack of correlation between the activity of the mesolimbic dopaminergic system and the rewarding properties of pregabalin in mouse. Psychopharmacology (Berl) 2019; 236:2069-2082. [PMID: 30879119 DOI: 10.1007/s00213-019-05198-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 02/13/2019] [Indexed: 12/21/2022]
Abstract
RATIONALE Pregabalin is a psychoactive drug indicated in the treatment of epilepsy, neuropathic pain, and generalized anxiety disorders. Pregabalin acts on different neurotransmission systems by inactivating the alpha2-delta subunit of voltage-gated calcium channels. In light of this pharmacological property, the hypothesis has been raised that pregabalin may regulate the mesolimbic dopamine pathway and thereby display a potential for misuse or abuse as recently observed in humans. Although some preclinical data support this possibility, the rewarding properties of gabapentinoid are still a matter for debate. OBJECTIVE The aim of this work was to evaluate the rewarding properties of pregabalin and to determine its putative mechanism of action in healthy mice. RESULTS Pregabalin alone (60 mg/kg; s.c.) produced a rewarding effect in the conditioned place preference (CPP) test albeit to a lower extent than cocaine (30 mg/kg; s.c.). Interestingly, when assessing locomotor activity in the CPP, the PGB60 group, similarly to the cocaine group, showed an increased locomotor activity. In vivo single unit extracellular recording showed that pregabalin had mixed effects on dopamine (DA) neuronal activity in the ventral tegmental area since it decreased the activity of 50% of neurons and increased 28.5% of them. In contrast, cocaine decreased 75% of VTA DA neuronal activity whereas none of the neurons were activated. Intracerebal microdialysis was then conducted in awake freely mice to determine to what extent such electrophysiological parameters influence the extracellular DA concentrations ([DA]ext) in the nucleus accumbens. Although pregabalin failed to modify this parameter, cocaine produced a robust increase (800%) in [DA]ext. CONCLUSIONS Collectively, these electrophysiological and neurochemical experiments suggest that the rewarding properties of pregabalin result from a different mode of action than that observed with cocaine. Further experiments are warranted to determine whether such undesirable effects can be potentiated under pathological conditions such as neuropathic pain, mood disorders, or addiction and to identify the key neurotransmitter system involved.
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Affiliation(s)
- Basile Coutens
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, Bât4R3, 118 Route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Lionel Mouledous
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, Bât4R3, 118 Route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Manta Stella
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, Bât4R3, 118 Route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Claire Rampon
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, Bât4R3, 118 Route de Narbonne, 31062, Toulouse, Cedex 09, France
| | - Maryse Lapeyre-Mestre
- Pharmacoepidemiology Research Unit, INSERM-Université Toulouse 3, UMR 1027, 31000, Toulouse, France
| | - Anne Roussin
- Pharmacoepidemiology Research Unit, INSERM-Université Toulouse 3, UMR 1027, 31000, Toulouse, France
| | - Bruno P Guiard
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université Paul Sabatier Toulouse III, Bât4R3, 118 Route de Narbonne, 31062, Toulouse, Cedex 09, France. .,Faculté de Pharmacie, Université Paris Sud, Université Paris-Saclay, 92290, Chatenay-Malabry, France. .,CNRS UMR-5169, UPS, 31000, Toulouse, France.
| | - Emilie Jouanjus
- Pharmacoepidemiology Research Unit, INSERM-Université Toulouse 3, UMR 1027, 31000, Toulouse, France
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16
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Thibeault KC, Kutlu MG, Sanders C, Calipari ES. Cell-type and projection-specific dopaminergic encoding of aversive stimuli in addiction. Brain Res 2019; 1713:1-15. [PMID: 30580012 PMCID: PMC6506354 DOI: 10.1016/j.brainres.2018.12.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 11/26/2018] [Accepted: 12/16/2018] [Indexed: 01/02/2023]
Abstract
Drug addiction is a major public health concern across the world for which there are limited treatment options. In order to develop new therapies to correct the behavioral deficits that result from repeated drug use, we need to understand the neural circuit dysfunction that underlies the pathophysiology of the disorder. Because the initial reinforcing effects of drugs are dependent on increases in dopamine in reward-related brain regions such as the mesolimbic dopamine pathway, a large focus of addiction research has centered on the dysregulation of this system and its control of positive reinforcement and motivation. However, in addition to the processing of positive, rewarding stimuli, there are clear deficits in the encoding and valuation of information about potential negative outcomes and how they control decision making and motivation. Further, aversive stimuli can motivate or suppress behavior depending on the context in which they are encountered. We propose a model where rewarding and aversive information guides the execution of specific motivated actions through mesocortical and mesolimbic dopamine acting on D1- and D2- receptor containing neuronal populations. Volitional drug exposure alters the processing of rewarding and aversive stimuli through remodeling of these dopaminergic circuits, causing maladaptive drug seeking, self-administration in the face of negative consequences, and drug craving. Together, this review discusses the dysfunction of the circuits controlling different types of aversive learning as well as how these guide specific discrete behaviors, and provides a conceptual framework for how they should be considered in preclinical addiction models.
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Affiliation(s)
- Kimberly C Thibeault
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Munir Gunes Kutlu
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Christina Sanders
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Erin S Calipari
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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17
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Nestler EJ, Lüscher C. The Molecular Basis of Drug Addiction: Linking Epigenetic to Synaptic and Circuit Mechanisms. Neuron 2019; 102:48-59. [PMID: 30946825 PMCID: PMC6587180 DOI: 10.1016/j.neuron.2019.01.016] [Citation(s) in RCA: 169] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/01/2019] [Accepted: 01/10/2019] [Indexed: 12/22/2022]
Abstract
Addiction is a disease in which, after a period of recreational use, a subset of individuals develops compulsive use that does not stop even in light of major negative consequences. Here, we review the evidence for underlying epigenetic remodeling in brain in two settings. First, excessive dopamine signaling during drug use may modulate gene expression, altering synaptic function and circuit activity and leading over time to maladaptive behaviors in vulnerable individuals. Second, on a longer timescale, life experience can shape the epigenetic landscape in brain and thereby may contribute to an individual's vulnerability by amplifying drug-induced changes in gene expression that drive the transition to addiction. We conclude by exploring how epigenetic mechanisms might serve as therapeutic targets for addiction treatments.
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Affiliation(s)
- Eric J Nestler
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Christian Lüscher
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Clinic of Neurology, Departement of Clinical Neurosiences, Geneva University Hospital, Geneva, Switzerland.
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18
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Weele CMV, Siciliano CA, Tye KM. Dopamine tunes prefrontal outputs to orchestrate aversive processing. Brain Res 2018; 1713:16-31. [PMID: 30513287 DOI: 10.1016/j.brainres.2018.11.044] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 11/25/2018] [Accepted: 11/30/2018] [Indexed: 01/06/2023]
Abstract
Decades of research suggest that the mesocortical dopamine system exerts powerful control over mPFC physiology and function. Indeed, dopamine signaling in the medial prefrontal cortex (mPFC) is implicated in a vast array of processes, including working memory, stimulus discrimination, stress responses, and emotional and behavioral control. Consequently, even slight perturbations within this delicate system result in profound disruptions of mPFC-mediated processes. Many neuropsychiatric disorders are associated with dysregulation of mesocortical dopamine, including schizophrenia, depression, attention deficit hyperactivity disorder, post-traumatic stress disorder, among others. Here, we review the anatomy and functions of the mesocortical dopamine system. In contrast to the canonical role of striatal dopamine in reward-related functions, recent work has revealed that mesocortical dopamine fine-tunes distinct efferent projection populations in a manner that biases subsequent behavior towards responding to stimuli associated with potentially aversive outcomes. We propose a framework wherein dopamine can serve as a signal for switching mPFC states by orchestrating how information is routed to the rest of the brain.
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Affiliation(s)
- Caitlin M Vander Weele
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Cody A Siciliano
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kay M Tye
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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19
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Burton AC, Bissonette GB, Vazquez D, Blume EM, Donnelly M, Heatley KC, Hinduja A, Roesch MR. Previous cocaine self-administration disrupts reward expectancy encoding in ventral striatum. Neuropsychopharmacology 2018; 43:2350-2360. [PMID: 29728645 PMCID: PMC6180050 DOI: 10.1038/s41386-018-0058-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/06/2018] [Accepted: 03/27/2018] [Indexed: 01/16/2023]
Abstract
The nucleus accumbens core (NAc) is important for integrating and providing information to downstream areas about the timing and value of anticipated reward. Although NAc is one of the first brain regions to be affected by drugs of abuse, we still do not know how neural correlates related to reward expectancy are affected by previous cocaine self-administration. To address this issue, we recorded from single neurons in the NAc of rats that had previously self-administered cocaine or sucrose (control). Neural recordings were then taken while rats performed an odor-guided decision-making task in which we independently manipulated value of expected reward by changing the delay to or size of reward across a series of trial blocks. We found that previous cocaine self-administration made rats more impulsive, biasing choice behavior toward more immediate reward. Further, compared to controls, cocaine-exposed rats showed significantly fewer neurons in the NAc that were responsive during odor cues and reward delivery, and in the reward-responsive neurons that remained, diminished directional and value encoding was observed. Lastly, we found that after cocaine exposure, reward-related firing during longer delays was reduced compared to controls. These results demonstrate that prior cocaine self-administration alters reward-expectancy encoding in NAc, which could contribute to poor decision making observed after chronic cocaine use.
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Affiliation(s)
- Amanda C Burton
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
- Program in Neuroscience and Cognitive Science, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Gregory B Bissonette
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
- Program in Neuroscience and Cognitive Science, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Daniela Vazquez
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Elyse M Blume
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Maria Donnelly
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Kendall C Heatley
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Abhishek Hinduja
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA
| | - Matthew R Roesch
- Department of Psychology, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA.
- Program in Neuroscience and Cognitive Science, 1147 Biology-Psychology Building University of Maryland, College Park, MD, 20742, USA.
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20
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Corre J, van Zessen R, Loureiro M, Patriarchi T, Tian L, Pascoli V, Lüscher C. Dopamine neurons projecting to medial shell of the nucleus accumbens drive heroin reinforcement. eLife 2018; 7:39945. [PMID: 30373717 PMCID: PMC6207421 DOI: 10.7554/elife.39945] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 10/17/2018] [Indexed: 12/21/2022] Open
Abstract
The dopamine (DA) hypothesis posits the increase of mesolimbic dopamine levels as a defining commonality of addictive drugs, initially causing reinforcement, eventually leading to compulsive consumption. While much experimental evidence from psychostimulants supports this hypothesis, it has been challenged for opioid reinforcement. Here, we monitor genetically encoded DA and calcium indicators as well as cFos in mice to reveal that heroin activates DA neurons located in the medial part of the VTA, preferentially projecting to the medial shell of the nucleus accumbens (NAc). Chemogenetic and optogenetic manipulations of VTA DA or GABA neurons establish a causal link to heroin reinforcement. Inhibition of DA neurons blocked heroin self-administration, while heroin inhibited optogenetic self-stimulation of DA neurons. Likewise, heroin occluded the self-inhibition of VTA GABA neurons. Together, these experiments support a model of disinhibition of a subset of VTA DA neurons in opioid reinforcement.
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Affiliation(s)
- Julie Corre
- Department of Basic Neurosciences, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Ruud van Zessen
- Department of Basic Neurosciences, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Michaël Loureiro
- Department of Basic Neurosciences, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Tommaso Patriarchi
- School of Medicine, Department of Biochemistry and Molecular Medicine, University of California Davis, California, United States
| | - Lin Tian
- School of Medicine, Department of Biochemistry and Molecular Medicine, University of California Davis, California, United States
| | - Vincent Pascoli
- Department of Basic Neurosciences, Medical Faculty, University of Geneva, Geneva, Switzerland
| | - Christian Lüscher
- Department of Basic Neurosciences, Medical Faculty, University of Geneva, Geneva, Switzerland.,Service of Neurology, University of Geneva Hospital, Geneva, Switzerland
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21
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Akhiary M, Purvis EM, Klein AK, Ettenberg A. Methamphetamine self-administration in a runway model of drug-seeking behavior in male rats. Pharmacol Biochem Behav 2018; 175:27-32. [PMID: 30196087 DOI: 10.1016/j.pbb.2018.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/27/2022]
Abstract
Cocaine administration has been shown to produce immediate positive (rewarding) and subsequent negative (anxiogenic) effects in humans and animals. These dual and opposing affective responses have been more difficult to demonstrate with administration of methamphetamine (meth). While animal studies have reliably demonstrated the positive reinforcing effects of the drug, reports of negative aftereffects following acute exposure have been few in number and contradictory in nature. The current research was devised to assess the effects of acute meth using a runway model of self-administration that is uniquely sensitive to both the positive and negative effects of a drug reinforcer in the same animal on the same trial. Male rats were allowed to traverse a straight alley once a day for 16 consecutive days/trials where entry into the goal box resulted in a single IV injection of meth (0.25, 0.5 or 1.0 mg/kg/inj.). The chosen doses were confirmed to be psychoactive as they produced dose-dependent increases in motoric/locomotor activation in these same subjects. The results demonstrated a U-shaped dose-response curve for the reinforcing effects of meth in that the intermediate dose group (0.5 mg/kg) produced the strongest approach behavior in the runway. Unlike other psychomotor stimulants, like cocaine, animals running for IV meth exhibited no evidence of any significant approach-avoidance behaviors reflective of the drug's negative anxiogenic effects. These results suggest that the abuse potential for meth is likely higher than for other shorter-acting psychomotor stimulants and reaffirms the utility of the runway procedure as a screen for a substance's abuse potential.
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Affiliation(s)
- Mona Akhiary
- Behavioral Pharmacology Laboratory, Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA 93109-9660, USA
| | - Erin M Purvis
- Behavioral Pharmacology Laboratory, Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA 93109-9660, USA
| | - Adam K Klein
- Behavioral Pharmacology Laboratory, Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA 93109-9660, USA
| | - Aaron Ettenberg
- Behavioral Pharmacology Laboratory, Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA 93109-9660, USA.
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22
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Fitzpatrick CJ, Jagannathan L, Lowenstein ED, Robinson TE, Becker JB, Morrow JD. Single prolonged stress decreases sign-tracking and cue-induced reinstatement of cocaine-seeking. Behav Brain Res 2018; 359:799-806. [PMID: 30077578 DOI: 10.1016/j.bbr.2018.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/27/2018] [Accepted: 07/27/2018] [Indexed: 11/19/2022]
Abstract
Exposure to prolonged, uncontrollable stress reduces reward-seeking behavior, resulting in anhedonia in neuropsychiatric disorders, such as posttraumatic stress disorder. However, it is unclear to what degree stressed subjects lose interest in rewards themselves or in reward-related cues that instigate reward-seeking behavior. In the present study, we investigated the effects of single prolonged stress (SPS) on cue-directed behavior in two different procedures: Pavlovian conditioned approach (PCA) and cue-induced reinstatement of cocaine-seeking. In Experiment 1, rats were exposed to SPS and tested for the acquisition of sign-tracking (cue-directed) and goal-tracking (reward-directed) behaviors during a PCA procedure. In Experiment 2, rats were exposed to SPS and tested for the expression of sign- and goal-tracking as well as cue-induced reinstatement of cocaine-seeking. Because dopaminergic activity in the nucleus accumbens is known to play a central role in many cue-directed behaviors, including both sign-tracking and cue-induced reinstatement, Experiment 3 used in vivo microdialysis to measure the effect of SPS on baseline and evoked dopamine levels in the nucleus accumbens. SPS decreased sign-tracking and increased goal-tracking during the acquisition of PCA behavior without affecting reward consumption. In addition, SPS decreased cue-induced reinstatement without affecting cocaine self-administration. Finally, SPS decreased evoked but not baseline levels of dopamine in the nucleus accumbens. These results suggest that SPS decreases the motivational, but not consummatory, aspects of reward-seeking behavior, which may result from long-term, SPS-induced reductions in dopamine release in the nucleus accumbens.
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Affiliation(s)
| | | | | | - Terry E Robinson
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA; Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jill B Becker
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA; Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jonathan D Morrow
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA; Department of Psychiatry, University of Michigan, Ann Arbor, MI 48109, USA.
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23
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Phasic Stimulation of Midbrain Dopamine Neuron Activity Reduces Salt Consumption. eNeuro 2018; 5:eN-NWR-0064-18. [PMID: 29766048 PMCID: PMC5952649 DOI: 10.1523/eneuro.0064-18.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/12/2018] [Accepted: 03/13/2018] [Indexed: 01/13/2023] Open
Abstract
Salt intake is an essential dietary requirement, but excessive consumption is implicated in hypertension and associated conditions. Little is known about the neural circuit mechanisms that control motivation to consume salt, although the midbrain dopamine system, which plays a key role in other reward-related behaviors, has been implicated. We, therefore, examined the effects on salt consumption of either optogenetic excitation or chemogenetic inhibition of ventral tegmental area (VTA) dopamine neurons in male mice. Strikingly, optogenetic excitation of dopamine neurons decreased salt intake in a rapid and reversible manner, despite a strong salt appetite. Importantly, optogenetic excitation was not aversive, did not induce hyperactivity, and did not alter salt concentration preferences in a need-free state. In addition, we found that chemogenetic inhibition of dopamine neurons had no effect on salt intake. Lastly, optogenetic excitation of dopamine neurons reduced consumption of sucrose following an overnight fast, suggesting a more general role of VTA dopamine neuron excitation in organizing motivated behaviors.
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24
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Pelloux Y, Hoots JK, Cifani C, Adhikary S, Martin J, Minier-Toribio A, Bossert JM, Shaham Y. Context-induced relapse to cocaine seeking after punishment-imposed abstinence is associated with activation of cortical and subcortical brain regions. Addict Biol 2018; 23:699-712. [PMID: 28661034 DOI: 10.1111/adb.12527] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 05/03/2017] [Accepted: 05/09/2017] [Indexed: 12/31/2022]
Abstract
We recently developed a rat model of context-induced relapse to alcohol seeking after punishment-imposed abstinence to mimic relapse after self-imposed abstinence due to adverse consequences of drug use. Here, we determined the model's generality to cocaine and have begun to explore brain mechanisms of context-induced relapse to cocaine seeking after punishment-imposed abstinence, using the activity marker Fos. In exp. 1, we trained rats to self-administer cocaine (0.75 mg/kg/infusion, 6 hours/day, 12 days) in context A. Next, we transferred them to context B where for the paired group, but not unpaired group, 50 percent of cocaine-reinforced lever presses caused aversive footshock. We then tested the rats for cocaine seeking under extinction conditions in contexts A and B. We also retested them for relapse after retraining in context A and repunishment in context B. In exp. 2, we used Fos immunoreactivity to determine relapse-associated neuronal activation in brain regions of rats exposed to context A, context B or neither context. Results showed the selective shock-induced suppression of cocaine self-administration and context-induced relapse after punishment-imposed abstinence in rats exposed to paired, but not unpaired, footshock. Additionally, context-induced relapse was associated with selective activation of dorsal and ventral medial prefrontal cortex, anterior insula, dorsal striatum, basolateral amygdala, paraventricular nucleus of the thalamus, lateral habenula, substantia nigra, ventral subiculum, and dorsal raphe, but not nucleus accumbens, central amygdala, lateral hypothalamus, ventral tegmental area and other brain regions. Together, context-induced relapse after punishment-imposed abstinence generalizes to rats with a history of cocaine self-administration and is associated with selective activation of cortical and subcortical regions.
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Affiliation(s)
- Yann Pelloux
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
| | - Jennifer K. Hoots
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
| | - Carlo Cifani
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
- School of Pharmacy, Pharmacology Unit; University of Camerino; Italy
| | - Sweta Adhikary
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
| | - Jennifer Martin
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
| | | | - Jennifer M. Bossert
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
| | - Yavin Shaham
- Behavioral Neuroscience Branch; Intramural Research Program; Baltimore MD USA
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25
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Amphetamine Reverses Escalated Cocaine Intake via Restoration of Dopamine Transporter Conformation. J Neurosci 2017; 38:484-497. [PMID: 29175958 DOI: 10.1523/jneurosci.2604-17.2017] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 12/27/2022] Open
Abstract
Cocaine abuse disrupts dopamine system function, and reduces cocaine inhibition of the dopamine transporter (DAT), which results in tolerance. Although tolerance is a hallmark of cocaine addiction and a DSM-V criterion for substance abuse disorders, the molecular adaptations producing tolerance are unknown, and testing the impact of DAT changes on drug taking behaviors has proven difficult. In regard to treatment, amphetamine has shown efficacy in reducing cocaine intake; however, the mechanisms underlying these effects have not been explored. The goals of this study were twofold; we sought to (1) identify the molecular mechanisms by which cocaine exposure produces tolerance and (2) determine whether amphetamine-induced reductions in cocaine intake are connected to these mechanisms. Using cocaine self-administration and fast-scan cyclic voltammetry in male rats, we show that low-dose, continuous amphetamine treatment, during self-administration or abstinence, completely reversed cocaine tolerance. Amphetamine treatment also reversed escalated cocaine intake and decreased motivation to obtain cocaine as measured in a behavioral economics task, thereby linking tolerance to multiple facets of cocaine use. Finally, using fluorescence resonance energy transfer imaging, we found that cocaine tolerance is associated with the formation of DAT-DAT complexes, and that amphetamine disperses these complexes. In addition to extending our basic understanding of DATs and their role in cocaine reinforcement, we serendipitously identified a novel therapeutic target: DAT oligomer complexes. We show that dispersion of oligomers is concomitant with reduced cocaine intake, and propose that pharmacotherapeutics aimed at these complexes may have potential for cocaine addiction treatment.SIGNIFICANCE STATEMENT Tolerance to cocaine's subjective effects is a cardinal symptom of cocaine addiction and a DSM-V criterion for substance abuse disorders. However, elucidating the molecular adaptions that produce tolerance and determining its behavioral impact have proven difficult. Using cocaine self-administration in rats, we link tolerance to cocaine effects at the dopamine transporter (DAT) with aberrant cocaine-taking behaviors. Further, tolerance was associated with multi-DAT complexes, which formed after cocaine exposure. Treatment with amphetamine deconstructed DAT complexes, reversed tolerance, and decreased cocaine seeking. These data describe the behavioral consequence of cocaine tolerance, provide a putative mechanism for its development, and suggest that compounds that disperse DAT complexes may be efficacious treatments for cocaine addiction.
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26
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Cross-talk between the epigenome and neural circuits in drug addiction. PROGRESS IN BRAIN RESEARCH 2017; 235:19-63. [PMID: 29054289 DOI: 10.1016/bs.pbr.2017.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Drug addiction is a behavioral disorder characterized by dysregulated learning about drugs and associated cues that result in compulsive drug seeking and relapse. Learning about drug rewards and predictive cues is a complex process controlled by a computational network of neural connections interacting with transcriptional and molecular mechanisms within each cell to precisely guide behavior. The interplay between rapid, temporally specific neuronal activation, and longer-term changes in transcription is of critical importance in the expression of appropriate, or in the case of drug addiction, inappropriate behaviors. Thus, these factors and their interactions must be considered together, especially in the context of treatment. Understanding the complex interplay between epigenetic gene regulation and circuit connectivity will allow us to formulate novel therapies to normalize maladaptive reward behaviors, with a goal of modulating addictive behaviors, while leaving natural reward-associated behavior unaffected.
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Cocaine Potency at the Dopamine Transporter Tracks Discrete Motivational States During Cocaine Self-Administration. Neuropsychopharmacology 2017; 42:1893-1904. [PMID: 28139678 PMCID: PMC5520781 DOI: 10.1038/npp.2017.24] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/23/2016] [Accepted: 01/12/2017] [Indexed: 02/07/2023]
Abstract
Although the dopamine transporter (DAT) is the primary site of action for cocaine, and the dopamine system is known to mediate the reinforcing effects of cocaine, the dopaminergic variations underlying individual differences in cocaine self-administration behaviors are not fully understood. Recent advances in the application of economic principles to operant tasks in rodents have allowed for the within-subject, within-session determination of both consummatory and appetitive responding for reinforcers. Here we combined a behavioral economics approach with cocaine self-administration and ex vivo voltammetric recording of dopamine signaling in the core of the nucleus accumbens of rats to determine the relationship between dopamine signaling and discrete aspects of cocaine taking and seeking. We found neither dopamine release or uptake tracked individual differences in cocaine consumption or the reinforcing efficacy of cocaine. Cocaine potency at the DAT was correlated with reinforcing efficacy, but was not related to cocaine consumption. Further, we introduce a novel analysis that determines perseverative responding within the same procedure, and find that cocaine potency at the DAT also tracks differences in perseverative responding. Together, we demonstrate that cocaine effects at the DAT determine the reinforcing efficacy of cocaine, and perseverative responding for sub-threshold doses of cocaine that do not maintain responding when presented in isolation. Surprisingly, we find that variations in cocaine potency do not account for differences in cocaine consumption, suggesting that satiation for cocaine is determined by other targets or mechanisms. Finally, we outline a novel approach for relating drug-target interactions and potency to discrete motivational states during a single self-administration session.
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Drug-Induced Alterations of Endocannabinoid-Mediated Plasticity in Brain Reward Regions. J Neurosci 2017; 36:10230-10238. [PMID: 27707960 DOI: 10.1523/jneurosci.1712-16.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/25/2016] [Indexed: 12/21/2022] Open
Abstract
The endocannabinoid (eCB) system has emerged as one of the most important mediators of physiological and pathological reward-related synaptic plasticity. eCBs are retrograde messengers that provide feedback inhibition, resulting in the suppression of neurotransmitter release at both excitatory and inhibitory synapses, and they serve a critical role in the spatiotemporal regulation of both short- and long-term synaptic plasticity that supports adaptive learning of reward-motivated behaviors. However, mechanisms of eCB-mediated synaptic plasticity in reward areas of the brain are impaired following exposure to drugs of abuse. Because of this, it is theorized that maladaptive eCB signaling may contribute to the development and maintenance of addiction-related behavior. Here we review various forms of eCB-mediated synaptic plasticity present in regions of the brain involved in reward and reinforcement and explore the potential physiological relevance of maladaptive eCB signaling to addiction vulnerability.
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Fredriksson I, Adhikary S, Steensland P, Vendruscolo LF, Bonci A, Shaham Y, Bossert JM. Prior Exposure to Alcohol Has No Effect on Cocaine Self-Administration and Relapse in Rats: Evidence from a Rat Model that Does Not Support the Gateway Hypothesis. Neuropsychopharmacology 2017; 42:1001-1011. [PMID: 27649640 PMCID: PMC5506787 DOI: 10.1038/npp.2016.209] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/02/2016] [Accepted: 09/13/2016] [Indexed: 12/13/2022]
Abstract
The gateway hypothesis posits that initial exposure to legal drugs promotes subsequent addiction to illicit drugs. However, epidemiological studies are correlational and cannot rule out the alternative hypothesis of shared addiction vulnerability to legal and illegal drugs. We tested the gateway hypothesis using established rat alcohol exposure procedures and cocaine self-administration and reinstatement (relapse) procedures. We gave Wistar or alcohol-preferring (P) rats intermittent access to water or 20% alcohol in their homecage for 7 weeks (three 24-h sessions/week). We also exposed Wistar rats to air or intoxicating alcohol levels in vapor chambers for 14-h/day for 7 weeks. We then tested the groups of rats for acquisition of cocaine self-administration using ascending cocaine doses (0.125, 0.25, 0.5, 1.0 mg/kg/infusion) followed by a dose-response curve after acquisition of cocaine self-administration. We then extinguished lever pressing and tested the rats for reinstatement of drug seeking induced by cocaine-paired cues and cocaine priming (0, 2.5, 5, 10 mg/kg, i.p.). Wistar rats consumed moderate amounts of alcohol (4.6 g/kg/24 h), P rats consumed higher amounts of alcohol (7.6 g/kg/24 h), and Wistar rats exposed to alcohol vapor had a mean blood alcohol concentration of 176.2 mg/dl during the last week of alcohol exposure. Alcohol pre-exposure had no effect on cocaine self-administration, extinction responding, and reinstatement of drug seeking. Pre-exposure to moderate, high, or intoxicating levels of alcohol had no effect on cocaine self-administration and relapse to cocaine seeking. Our data do not support the notion that alcohol is a gateway drug to cocaine.
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Affiliation(s)
- Ida Fredriksson
- Cellular Neurobiology Branch, IRP-NIDA, NIH, Baltimore, MD, USA,Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet & Stockholm Health Care Services, Stockholm, Sweden
| | - Sweta Adhikary
- Behavioral Neuroscience Branch, IRP-NIDA, NIH, Baltimore, MD, USA
| | - Pia Steensland
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet & Stockholm Health Care Services, Stockholm, Sweden
| | | | - Antonello Bonci
- Cellular Neurobiology Branch, IRP-NIDA, NIH, Baltimore, MD, USA,Solomon H. Snyder Neuroscience Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA,Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yavin Shaham
- Behavioral Neuroscience Branch, IRP-NIDA, NIH, Baltimore, MD, USA,NIDA, IRP Behavioral Neuroscience Branch 251 Bayview Blvd, Suite 200, Baltimore, MD 21044, USA, Tel: +1 410 740-2723, Fax: +1 410 740-2727, E-mail:
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Cholinergic Interneurons Underlie Spontaneous Dopamine Release in Nucleus Accumbens. J Neurosci 2017; 37:2086-2096. [PMID: 28115487 DOI: 10.1523/jneurosci.3064-16.2017] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 12/27/2016] [Accepted: 01/13/2017] [Indexed: 12/13/2022] Open
Abstract
The release of dopamine from terminals in the NAc is regulated by a number of factors, including voltage-gated ion channels, D2-autoreceptors, and nAChRs. Cholinergic interneurons (CINs) drive dopamine release through activation of nAChRs on dopamine terminals. Using cyclic voltammetry in mouse brain slices, nAChR-dependent spontaneous dopamine transients and the mechanisms underlying the origin were examined in the NAc. Spontaneous events were infrequent (0.3 per minute), but the rate and amplitude were increased after blocking Kv channels with 4-aminopyridine. Although the firing frequency of CINs was increased by blocking glutamate reuptake with TBOA and the Sk blocker apamin, only 4-aminopyridine increased the frequency of dopamine transients. In contrast, inhibition of CIN firing with the μ/δ selective opioid [Met5]enkephalin (1 μm) decreased spontaneous dopamine transients. Cocaine increased the rate and amplitude of dopamine transients, suggesting that the activity of the dopamine transporter limits the detection of these events. In the presence of cocaine, the rate of spontaneous dopamine transients was further increased after blocking D2-autoreceptors. Blockade of muscarinic receptors had no effect on evoked dopamine release, suggesting that feedback inhibition of acetylcholine release was not involved. Thus, although spontaneous dopamine transients are reliant on nAChRs, the frequency was not strictly governed by the activity of CINs. The increase in frequency of spontaneous dopamine transients induced by cocaine was not due to an increase in cholinergic tone and is likely a product of an increase in detection resulting from decreased dopamine reuptake.SIGNIFICANCE STATEMENT The actions of dopamine in the NAc are thought to be responsible for endogenous reward and the reinforcing properties of drugs of abuse, such as psychostimulants. The present work examines the mechanisms underlying nAChR-induced spontaneous dopamine release. This study demonstrates that spontaneous dopamine release is (1) dependent of the activation of nicotinic receptors, (2) independent on the spontaneous activity of cholinergic interneurons, and (3) that cocaine increased the detection of dopamine transients by prolonging the presence and increasing the diffusion of dopamine in the extracellular space. The release of acetylcholine is therefore responsible for spontaneous dopamine transients, and cocaine augments dopamine tone without altering activity of cholinergic interneurons.
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Enduring, Sexually Dimorphic Impact of In Utero Exposure to Elevated Levels of Glucocorticoids on Midbrain Dopaminergic Populations. Brain Sci 2016; 7:brainsci7010005. [PMID: 28042822 PMCID: PMC5297294 DOI: 10.3390/brainsci7010005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/14/2016] [Accepted: 12/16/2016] [Indexed: 11/17/2022] Open
Abstract
Glucocorticoid hormones (GCs) released from the fetal/maternal glands during late gestation are required for normal development of mammalian organs and tissues. Accordingly, synthetic glucocorticoids have proven to be invaluable in perinatal medicine where they are widely used to accelerate fetal lung maturation when there is risk of pre-term birth and to promote infant survival. However, clinical and pre-clinical studies have demonstrated that inappropriate exposure of the developing brain to elevated levels of GCs, either as a result of clinical over-use or after stress-induced activation of the fetal/maternal adrenal cortex, is linked with significant effects on brain structure, neurological function and behaviour in later life. In order to understand the underlying neural processes, particular interest has focused on the midbrain dopaminergic systems, which are critical regulators of normal adaptive behaviours, cognitive and sensorimotor functions. Specifically, using a rodent model of GC exposure in late gestation (approximating human brain development at late second/early third trimester), we demonstrated enduring effects on the shape and volume of the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (origins of the mesocorticolimbic and nigrostriatal dopaminergic pathways) on the topographical organisation and size of the dopaminergic neuronal populations and astrocytes within these nuclei and on target innervation density and neurochemical markers of dopaminergic transmission (receptors, transporters, basal and amphetamine-stimulated dopamine release at striatal and prefrontal cortical sites) that impact on the adult brain. The effects of antenatal GC treatment (AGT) were both profound and sexually-dimorphic, not only in terms of quantitative change but also qualitatively, with several parameters affected in the opposite direction in males and females. Although such substantial neurobiological changes might presage marked behavioural effects, in utero GC exposure had only a modest or no effect, depending on sex, on a range of conditioned and unconditioned behaviours known to depend on midbrain dopaminergic transmission. Collectively, these findings suggest that apparent behavioural normality in certain tests, but not others, arises from AGT-induced adaptations or compensatory mechanisms within the midbrain dopaminergic systems, which preserve some, but not all functions. Furthermore, the capacities for molecular adaptations to early environmental challenge are different, even opponent, in males and females, which may account for their differential resilience or failure to perform adequately in behavioural tests. Behavioural "normality" is thus achieved by the midbrain dopaminergic network operating outside its normal limits (in a state of allostasis), rendering it at greater risk to malfunction when challenged in later life. Sex-specific neurobiological programming of midbrain dopaminergic systems may, therefore, have psychopathological relevance for the sex bias commonly found in brain disorders associated with these systems, and which have a neurodevelopmental component, including schizophrenia, ADHD (attention/deficit hyperactivity disorders), autism, depression and substance abuse.
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Ulrich M, Steigleder L, Grön G. Neural signature of the Food Craving Questionnaire (FCQ)-Trait. Appetite 2016; 107:303-310. [DOI: 10.1016/j.appet.2016.08.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 07/01/2016] [Accepted: 08/09/2016] [Indexed: 10/21/2022]
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Nicola SM. Reassessing wanting and liking in the study of mesolimbic influence on food intake. Am J Physiol Regul Integr Comp Physiol 2016; 311:R811-R840. [PMID: 27534877 PMCID: PMC5130579 DOI: 10.1152/ajpregu.00234.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/09/2016] [Indexed: 01/12/2023]
Abstract
Humans and animals such as rats and mice tend to overconsume calorie-dense foods, a phenomenon that likely contributes to obesity. One often-advanced explanation for why we preferentially consume sweet and fatty foods is that they are more "rewarding" than low-calorie foods. "Reward" has been subdivided into three interdependent psychological processes: hedonia (liking a food), reinforcement (formation of associations among stimuli, actions, and/or the food), and motivation (wanting the food). Research into these processes has focused on the mesolimbic system, which comprises both dopamine neurons in the ventral tegmental area and neurons in their major projection target, the nucleus accumbens. The mesolimbic system and closely connected structures are commonly referred to as the brain's "reward circuit." Implicit in this title is the assumption that "rewarding" experiences are generally the result of activity in this circuit. In this review, I argue that food intake and the preference for calorie-dense foods can be explained without reference to subjective emotions. Furthermore, the contribution of mesolimbic dopamine to food intake and preference may not be a general one of promoting or coordinating behaviors that result in the most reward or caloric intake but may instead be limited to the facilitation of a specific form of neural computation that results in conditioned approach behavior. Studies on the neural mechanisms of caloric intake regulation must address how sensory information about calorie intake affects not just the mesolimbic system but also many other forms of computation that govern other types of food-seeking and food-oriented behaviors.
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Affiliation(s)
- Saleem M Nicola
- Departments of Neuroscience and Psychiatry, Albert Einstein College of Medicine, Bronx, New York
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Cameron CM, Wightman RM, Carelli RM. One month of cocaine abstinence potentiates rapid dopamine signaling in the nucleus accumbens core. Neuropharmacology 2016; 111:223-230. [PMID: 27616012 DOI: 10.1016/j.neuropharm.2016.09.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/29/2016] [Accepted: 09/06/2016] [Indexed: 11/17/2022]
Abstract
Cocaine addiction is a chronic relapsing disorder that is difficult to treat in part because addicts relapse even after extended periods of abstinence. Given the importance of the mesolimbic dopamine (DA) system in drug addiction, we sought to characterize cocaine abstinence induced changes in rapid DA signaling in the nucleus accumbens (NAc). Here, rats were trained to self-administer cocaine for 14 consecutive days, then divided into two groups. Day 1 rats (D1; n = 7) underwent 24 h of abstinence; Day 30 rats (D30; n = 7) underwent one month of abstinence. After abstinence, all rats underwent a single extinction session. Immediately after, rats were deeply anesthetized and fast scan cyclic voltammetry (FSCV) was used to measure DA release and uptake dynamics in the NAc core before and following a single cocaine injection. We show that one month of cocaine abstinence potentiates the peak concentration of electrically evoked DA in the NAc core following an acute injection of cocaine. This potentiation is not related to alterations in DA uptake parameters, which are unchanged following abstinence, but may reflect alterations in release. These results further support the abundance of literature showing that cocaine abstinence induces neuroplasticity in brain areas implicated in drug reward and relapse. The present findings also demonstrate critical differences between abstinence-induced neuroadaptations in DA signaling and those caused by drug exposure itself.
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Affiliation(s)
- Courtney M Cameron
- Department of Psychology and Neuroscience, The University of North Carolina, Chapel Hill, NC, USA
| | - R Mark Wightman
- Department of Chemistry, The University of North Carolina, Chapel Hill, NC, USA
| | - Regina M Carelli
- Department of Psychology and Neuroscience, The University of North Carolina, Chapel Hill, NC, USA.
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35
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Zaniewska M, Filip M, Przegalinski E. The Involvement of Norepinephrine in Behaviors Related to Psychostimulant Addiction. Curr Neuropharmacol 2016; 13:407-18. [PMID: 26411968 PMCID: PMC4812804 DOI: 10.2174/1570159x13666150121225659] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although it is generally accepted that the abuse-related effects of
amphetamines and cocaine result from the activation of the brain dopaminergic
(DA) system, the psychostimulants also alter other neurotransmitter systems. In
particular, they increase extracellular levels of norepinephrine (NE) and
serotonin by inhibiting respective plasma membrane transporters and/or inducing
release. The present review will discuss the preclinical findings on the effects
of the NE system modulation (lesions, pharmacological and genetic approaches) on
behaviors (locomotor hyperactivity, behavioral sensitization, modification of
intracranial self-stimulation, conditioned place preference, drug
self-administration, extinction/reinstatement of drug seeking behavior) related
to the psychostimulant addiction.
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Affiliation(s)
- Magdalena Zaniewska
- Laboratory of Drug Addiction Pharmacology, Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland.
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Abstract
Addiction is a disease of altered behavior. Addicts use drugs compulsively and will continue to do so despite negative consequences. Even after prolonged periods of abstinence, addicts are at risk of relapse, particularly when cues evoke memories that are associated with drug use. Rodent models mimic many of the core components of addiction, from the initial drug reinforcement to cue-associated relapse and continued drug intake despite negative consequences. Rodent models have also enabled unprecedented mechanistic insight into addiction, revealing plasticity of glutamatergic synaptic transmission evoked by the strong activation of mesolimbic dopamine-a defining feature of all addictive drugs-as a neural substrate for these drug-adaptive behaviors. Cell type-specific optogenetic manipulations have allowed both identification of the relevant circuits and design of protocols to reverse drug-evoked plasticity and to establish links of causality with drug-adaptive behaviors. The emergence of a circuit model for addiction will open the door for novel therapies, such as deep brain stimulation.
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Affiliation(s)
- Christian Lüscher
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland; .,Clinic of Neurology, Department of Clinical Neurosciences, Geneva University Hospital, CH-1211 Geneva, Switzerland
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Affiliation(s)
- Hailan Hu
- Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou 310012, People's Republic of China;
- Center for Neuroscience, School of Medicine, Zhejiang University, Hangzhou 310058, People's Republic of China
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38
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Robbins T, Everitt B. Interaction of the Dopaminergic System With Mechanisms of Associative Learning and Cognition: Implications for Drug Abuse. Psychol Sci 2016. [DOI: 10.1111/1467-9280.00134] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The possible role of mechanisms of associative learning in drug abuse and addiction is considered with respect to psychomotor stimulant drugs such as cocaine and amphetamine. Although the initial sites of the reinforcing effects of these drugs are associated with the mesolimbic dopamine projection to the nucleus accumbens, other important neuromodulatory influences are identified. These include the amygdala, which appears to mediate the associative processes by which environmental stimuli come to control drug-seeking behavior. Possible parallel mechanisms by which stimulant drugs enhance effects of aversive as well as rewarding stimuli are discussed. The importance of attribution and context in determining relative rewarding and aversive effects is pointed out. These attributional and contextual factors may be a function of cortical regions that may themselves be impaired by chronic drug abuse, leading to further dysexecutive control over cognition and behavior.
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Affiliation(s)
- T.W. Robbins
- University of Cambridge, Cambridge, United Kingdom
| | - B.J. Everitt
- University of Cambridge, Cambridge, United Kingdom
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Shelton K, Bogyo K, Schick T, Ettenberg A. Pharmacological modulation of lateral habenular dopamine D2 receptors alters the anxiogenic response to cocaine in a runway model of drug self-administration. Behav Brain Res 2016; 310:42-50. [PMID: 27155504 DOI: 10.1016/j.bbr.2016.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 04/01/2016] [Accepted: 05/02/2016] [Indexed: 12/21/2022]
Abstract
Cocaine has long been known to produce an initial "high" followed by an aversive/anxiogenic "crash". While much is known about the neurobiology of cocaine's positive/rewarding effects, the mechanisms that give rise to the drug's negative/anxiogenic actions remain unclear. Recent research has implicated the lateral habenula (LHb) in the encoding of aversive events including the anxiogenic response to cocaine. Of particular interest in this regard are the reciprocal connections between the LHb and the ventral tegmental area (VTA). VTA-DA neurons innervate different subsets of LHb cells that in turn feedback upon and modulate VTA neuronal activity. Here we examined the impact of D2 receptor activation and inhibition on the anxiogenic response to cocaine using a runway model of self-administration that is sensitive to the dual and opposing effects of the drug. Male rats ran a straight alley for IV cocaine (1.0mg/kg) following bilateral intra-LHb infusions of the D2 receptor antagonist, cis-flupenthixol (0, 7.5 or 15μg/side) or the D2 agonist, sumanirole (0, 5 or 10μg/side). Vehicle-pretreated controls developed approach-avoidance conflict behaviors about goal-box entry reflective of the dual positive and negative effects of cocaine. These behaviors were significantly diminished during LHb-D2 receptor antagonism and increased by the LHb D2 receptor agonist. These results demonstrate that activity at the D2 receptor in the lateral habenula serves to modulate the anxiogenic response to cocaine.
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Affiliation(s)
- Kerisa Shelton
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106-9660, United States
| | - Kelsie Bogyo
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106-9660, United States
| | - Tinisha Schick
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106-9660, United States
| | - Aaron Ettenberg
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106-9660, United States.
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Zlebnik NE, Cheer JF. Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation? Annu Rev Neurosci 2016; 39:1-17. [PMID: 27023732 DOI: 10.1146/annurev-neuro-070815-014038] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Cannabis sativa plant has been used to treat various physiological and psychiatric conditions for millennia. Current research is focused on isolating potentially therapeutic chemical constituents from the plant for use in the treatment of many central nervous system disorders. Of particular interest is the primary nonpsychoactive constituent cannabidiol (CBD). Unlike Δ(9)-tetrahydrocannabinol (THC), CBD does not act through the cannabinoid type 1 (CB1) receptor but has many other receptor targets that may play a role in psychiatric disorders. Here we review preclinical and clinical data outlining the therapeutic efficacy of CBD for the treatment of motivational disorders such as drug addiction, anxiety, and depression. Across studies, findings suggest promising treatment effects and potentially overlapping mechanisms of action for CBD in these disorders and indicate the need for further systematic investigation of the viability of CBD as a psychiatric pharmacotherapy.
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Affiliation(s)
- Natalie E Zlebnik
- 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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Mejias-Aponte CA. Specificity and impact of adrenergic projections to the midbrain dopamine system. Brain Res 2016; 1641:258-73. [PMID: 26820641 DOI: 10.1016/j.brainres.2016.01.036] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 01/11/2016] [Accepted: 01/20/2016] [Indexed: 12/18/2022]
Abstract
Dopamine (DA) is a neuromodulator that regulates different brain circuits involved in cognitive functions, motor coordination, and emotions. Dysregulation of DA is associated with many neurological and psychiatric disorders such as Parkinson's disease and substance abuse. Several lines of research have shown that the midbrain DA system is regulated by the central adrenergic system. This review focuses on adrenergic interactions with midbrain DA neurons. It discusses the current neuroanatomy including source of adrenergic innervation, type of synapses, and adrenoceptors expression. It also discusses adrenergic regulation of DA cell activity and neurotransmitter release. Finally, it reviews several neurological and psychiatric disorders where changes in adrenergic system are associated with dysregulation of the midbrain DA system. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- Carlos A Mejias-Aponte
- National Institute on Drug Abuse Histology Core, Neuronal Networks Section, Integrative Neuroscience Research Branch, National Institute on Drug Abuse, Biomedical Research Center, 251 Bayview Blvd, Suite 200, Baltimore, MD 21224, USA.
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España RA, Schmeichel BE, Berridge CW. Norepinephrine at the nexus of arousal, motivation and relapse. Brain Res 2016; 1641:207-16. [PMID: 26773688 DOI: 10.1016/j.brainres.2016.01.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/14/2015] [Accepted: 01/01/2016] [Indexed: 12/13/2022]
Abstract
Arousal plays a critical role in cognitive, affective and motivational processes. Consistent with this, the dysregulation of arousal-related neural systems is implicated in a variety of psychiatric disorders, including addiction. Noradrenergic systems exert potent arousal-enhancing actions that involve signaling at α1- and β-noradrenergic receptors within a distributed network of subcortical regions. The majority of research into noradrenergic modulation of arousal has focused on the nucleus locus coeruleus. Nevertheless, anatomical studies demonstrate that multiple noradrenergic nuclei innervate subcortical arousal-related regions, providing a substrate for differential regulation of arousal across these distinct noradrenergic nuclei. The arousal-promoting actions of psychostimulants and other drugs of abuse contribute to their widespread abuse. Moreover, relapse can be triggered by a variety of arousal-promoting events, including stress and re-exposure to drugs of abuse. Evidence has long-indicated that norepinephrine plays an important role in relapse. Recent observations suggest that noradrenergic signaling elicits affectively-neutral arousal that is sufficient to reinstate drug seeking. Collectively, these observations indicate that norepinephrine plays a key role in the interaction between arousal, motivation, and relapse. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- Rodrigo A España
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.
| | - Brooke E Schmeichel
- National Institute on Drug Abuse, Intramural Research Program, Baltimore, MD, United States.
| | - Craig W Berridge
- Department of Psychology, University of Wisconsin, Madison, WI, United States.
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Memory Systems of the Basal Ganglia. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/b978-0-12-802206-1.00035-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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DREADD-Induced Silencing of the Medial Olfactory Tubercle Disrupts the Preference of Female Mice for Opposite-Sex Chemosignals(1,2,3). eNeuro 2015; 2:eN-NWR-0078-15. [PMID: 26478911 PMCID: PMC4603255 DOI: 10.1523/eneuro.0078-15.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/21/2015] [Accepted: 08/29/2015] [Indexed: 12/15/2022] Open
Abstract
Attraction to opposite-sex pheromones during rodent courtship involves a pathway that includes inputs to the medial amygdala (Me) from the main and accessory olfactory bulbs, and projections from the Me to nuclei in the medial hypothalamus that control reproduction. However, the consideration of circuitry that attributes hedonic properties to opposite-sex odors has been lacking. The medial olfactory tubercle (mOT) has been implicated in the reinforcing effects of natural stimuli and drugs of abuse. We performed a tract-tracing study wherein estrous female mice that had received injections of the retrograde tracer, cholera toxin B, into the mOT were exposed to volatile odors from soiled bedding. Both the anterior Me and ventral tegmental area sent direct projections to the mOT, of which a significant subset was selectively activated (expressed Fos protein) by testes-intact male (but not female) volatile odors from soiled bedding. Next, the inhibitory DREADD (designer receptors exclusively activated by designer drugs) receptor hM4Di was bilaterally expressed in the mOT of female mice. Urinary preferences were then assessed after intraperitoneal injection of either saline or clozapine-N-oxide (CNO), which binds to the hM4Di receptor to hyperpolarize infected neurons. After receiving CNO, estrous females lost their preference for male over female urinary odors, whereas the ability to discriminate these odors remained intact. Male odor preference returned after vehicle treatment in counterbalanced tests. There were no deficits in locomotor activity or preference for food odors when subject mice received CNO injections prior to testing. The mOT appears to be a critical segment in the pheromone–reward pathway of female mice.
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Ettenberg A, Fomenko V, Kaganovsky K, Shelton K, Wenzel JM. On the positive and negative affective responses to cocaine and their relation to drug self-administration in rats. Psychopharmacology (Berl) 2015; 232:2363-75. [PMID: 25662610 PMCID: PMC4465857 DOI: 10.1007/s00213-015-3873-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 01/15/2015] [Indexed: 02/06/2023]
Abstract
RATIONALE Acute cocaine administration produces an initial rewarding state followed by a dysphoric/anxiogenic "crash." OBJECTIVE The objective of this study was to determine whether individual differences in the relative value of cocaine's positive and negative effects would account for variations in subsequent drug self-administration. METHODS The dual actions of cocaine were assessed using a conditioned place test (where animals formed preferences for environments paired with the immediate rewarding effects of 1.0mg/kg i.v. cocaine or aversions of environments associated with the anxiogenic effects present 15-min postinjection) and a runway test (where animals developed approach-avoidance "retreat" behaviors about entering a goal box associated with cocaine delivery). Ranked scores from these two tests were then correlated with each other and with the escalation in the operant responding of the same subjects observed over 10 days of 1- or 6-h/day access to i.v. (0.4 mg/inj) cocaine self-administration. RESULTS Larger place preferences were associated with faster runway start latencies (r s = -0.64), but not with retreat frequency or run times; larger place aversions predicted slower runway start times (r s = 0.62), increased run times (r s = 0.65), and increased retreats (r s = 0.62); response escalation was observed in both the 1- and 6-h self-administration groups and was associated with increased CPPs (r s = 0.58) but not CPAs, as well as with faster run times (r s = -0.60). CONCLUSIONS Together, these data suggest that animals exhibiting a greater positive than negative response to acute (single daily injections of) cocaine are at the greatest risk for subsequent escalated cocaine self-administration, a presumed indicator of cocaine addiction.
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Affiliation(s)
- Aaron Ettenberg
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA.
| | - Vira Fomenko
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA
| | - Konstantin Kaganovsky
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA
| | - Kerisa Shelton
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA
| | - Jennifer M Wenzel
- Behavioral Pharmacology Laboratory, Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA
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Yap JJ, Chartoff EH, Holly EN, Potter DN, Carlezon WA, Miczek KA. Social defeat stress-induced sensitization and escalated cocaine self-administration: the role of ERK signaling in the rat ventral tegmental area. Psychopharmacology (Berl) 2015; 232:1555-69. [PMID: 25373870 PMCID: PMC4397167 DOI: 10.1007/s00213-014-3796-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/21/2014] [Indexed: 01/20/2023]
Abstract
RATIONALE Intermittent social defeat stress can induce neuroadaptations that promote compulsive drug taking. Within the mesocorticolimbic circuit, repeated cocaine administration activates extracellular signal-regulated kinase (ERK). OBJECTIVE The present experiments examine whether changes in ERK phosphorylation are necessary for the behavioral and neural adaptations that occur as a consequence of intermittent defeat stress. MATERIALS AND METHODS Rats were exposed to four brief intermittent defeats over the course of 10 days. Ten days after the last defeat, rats were challenged with cocaine (10 mg/kg, i.p.) or saline, and ERK activity was examined in mesocorticolimbic regions. To determine the role of ERK in defeat stress-induced behavioral sensitization, we bilaterally microinjected the MAPK/ERK kinase inhibitor U0126 (1 μg/side) or vehicle (20 % DMSO) into the ventral tegmental area (VTA) prior to each of four defeats. Ten days following the last defeat, locomotor activity was assessed for the expression of behavioral cross-sensitization to cocaine (10 mg/kg, i.p.). Thereafter, rats self-administered cocaine under fixed and progressive ratio schedules of reinforcement, including a 24-h continuous access "binge" (0.3 mg/kg/infusion). RESULTS We found that repeated defeat stress increased ERK phosphorylation in the VTA. Inhibition of VTA ERK prior to each social defeat attenuated the development of stress-induced sensitization and prevented stress-induced enhancement of cocaine self-administration during a continuous access binge. CONCLUSIONS These results suggest that enhanced activation of ERK in the VTA due to brief defeats is critical in the induction of sensitization and escalated cocaine taking.
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Affiliation(s)
- Jasmine J Yap
- Department of Psychology, Tufts University, Medford, MA, 02155, USA,
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Ikemoto S, Yang C, Tan A. Basal ganglia circuit loops, dopamine and motivation: A review and enquiry. Behav Brain Res 2015; 290:17-31. [PMID: 25907747 DOI: 10.1016/j.bbr.2015.04.018] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/09/2015] [Accepted: 04/11/2015] [Indexed: 12/26/2022]
Abstract
Dopamine neurons located in the midbrain play a role in motivation that regulates approach behavior (approach motivation). In addition, activation and inactivation of dopamine neurons regulate mood and induce reward and aversion, respectively. Accumulating evidence suggests that such motivational role of dopamine neurons is not limited to those located in the ventral tegmental area, but also in the substantia nigra. The present paper reviews previous rodent work concerning dopamine's role in approach motivation and the connectivity of dopamine neurons, and proposes two working models: One concerns the relationship between extracellular dopamine concentration and approach motivation. High, moderate and low concentrations of extracellular dopamine induce euphoric, seeking and aversive states, respectively. The other concerns circuit loops involving the cerebral cortex, basal ganglia, thalamus, epithalamus, and midbrain through which dopaminergic activity alters approach motivation. These models should help to generate hypothesis-driven research and provide insights for understanding altered states associated with drugs of abuse and affective disorders.
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Affiliation(s)
- Satoshi Ikemoto
- Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA.
| | - Chen Yang
- Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA
| | - Aaron Tan
- Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA
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Abstract
There is abundant evidence that the dopamine (DA) neurons that project to the nucleus accumbens play a central role in neurobiological mechanisms underpinning drug dependence. This chapter considers the ways in which these projections facilitate the addiction to nicotine and tobacco. It focuses on the complimentary roles of the two principal subdivisions of the nucleus accumbens, the accumbal core and shell, in the acquisition and maintenance of nicotine-seeking behavior. The ways in which tonic and phasic firing of the neurons contributes to the ways in which the accumbens mediate the behavioral responses to nicotine are also considered. Experimental studies suggest that nicotine has relatively weak addictive properties which are insufficient to explain the powerful addictive properties of tobacco smoke. This chapter discusses hypotheses that seek to explain this conundrum. They implicate both discrete sensory stimuli closely paired with the delivery of tobacco smoke and contextual stimuli habitually associated with the delivery of the drug. The mechanisms by which each type of stimulus influence tobacco dependence are hypothesized to depend upon the increased DA release and overflow, respectively, in the two subdivisions of the accumbens. It is suggested that a majority of pharmacotherapies for tobacco dependence are not more successful because they fail to address this important aspect of the dependence.
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Affiliation(s)
- David J K Balfour
- Medical Research Institute, Division of Neuroscience, Ninewells Hospital and Medical School, Dundee, DD1 9SY, Scotland,
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49
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Thomas EK, Drobatz KJ, Mandell DC. Presumptive cocaine toxicosis in 19 dogs: 2004-2012. J Vet Emerg Crit Care (San Antonio) 2014; 24:201-7. [PMID: 24739034 DOI: 10.1111/vec.12159] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 12/30/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To characterize the incidence, signalment, presenting complaint, history, clinical signs, diagnostic test results, complications, treatment, length of hospitalization, and outcome of dogs presenting with presumptive cocaine toxicosis. DESIGN Retrospective study from March 1, 2004 to March 1, 2012. SETTING Twenty-four hour urban university veterinary teaching hospital. ANIMALS Nineteen dogs presenting with clinical signs consistent with cocaine toxicosis and having a positive urine cocaine test. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS All dogs had neurological abnormalities including bilateral mydriasis (11/19 [58%]), hyperexcitability/hyperesthesia (10/19 [53%]), ataxia (8/19 [42%]), focal or generalized muscle tremors (8/19 [42%]), reduced mental awareness (6/19 [32%]), and seizures (3/19 [16%]). Other signs included weakness (7/19 [37%]), vomiting (6/19 [32%]), and lethargy (3/19 [16%]). Tachycardia was apparent in 10/19 (53%) dogs, hypertension in 4/19 (21%), and hyperthermia in 5/19 (26%). Sinus tachycardia was the only reported cardiac arrhythmia. Bloodwork findings included hyperglycemia in 4/19 (21%) dogs, and increased plasma lactate concentration in 9/19 (47%). Most dogs (16/19 [84%]) were hospitalized for supportive care, which generally included isotonic crystalloid fluid administration, and treatment with sedative or anxiolytic drugs including diazepam, midazolam, acepromazine, and chlorpromazine. Two dogs required further anticonvulsant therapy (phenobarbital and propofol) and 1 dog was treated with a constant rate infusion of esmolol. All dogs survived to discharge, and the median length of hospitalization was 15 hours (10-30 h). CONCLUSIONS Cocaine toxicosis was infrequently suspected. Neurological signs predominated, but cardiovascular alterations were also frequently reported. Hospitalization for monitoring and supportive care is recommended given the potential for life-threatening complications such as seizures, hypertensive crisis, and tachyarrhythmias. The prognosis for survival to hospital discharge can be good with the appropriate supportive care.
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Affiliation(s)
- Emily K Thomas
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA, 19104-6010
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Barker JM, Taylor JR, De Vries TJ, Peters J. Brain-derived neurotrophic factor and addiction: Pathological versus therapeutic effects on drug seeking. Brain Res 2014; 1628:68-81. [PMID: 25451116 DOI: 10.1016/j.brainres.2014.10.058] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/20/2014] [Accepted: 10/27/2014] [Indexed: 11/27/2022]
Abstract
Many abused drugs lead to changes in endogenous brain-derived neurotrophic factor (BDNF) expression in neural circuits responsible for addictive behaviors. BDNF is a known molecular mediator of memory consolidation processes, evident at both behavioral and neurophysiological levels. Specific neural circuits are responsible for storing and executing drug-procuring motor programs, whereas other neural circuits are responsible for the active suppression of these "seeking" systems. These seeking-circuits are established as associations are formed between drug-associated cues and the conditioned responses they elicit. Such conditioned responses (e.g. drug seeking) can be diminished either through a passive weakening of seeking- circuits or an active suppression of those circuits through extinction. Extinction learning occurs when the association between cues and drug are violated, for example, by cue exposure without the drug present. Cue exposure therapy has been proposed as a therapeutic avenue for the treatment of addictions. Here we explore the role of BDNF in extinction circuits, compared to seeking-circuits that "incubate" over prolonged withdrawal periods. We begin by discussing the role of BDNF in extinction memory for fear and cocaine-seeking behaviors, where extinction circuits overlap in infralimbic prefrontal cortex (PFC). We highlight the ability of estrogen to promote BDNF-like effects in hippocampal-prefrontal circuits and consider the role of sex differences in extinction and incubation of drug-seeking behaviors. Finally, we examine how opiates and alcohol "break the mold" in terms of BDNF function in extinction circuits.
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Affiliation(s)
- Jacqueline M Barker
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Jane R Taylor
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Taco J De Vries
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, 1081 BT Amsterdam, The Netherlands; Department of Molecular and Cellular Neurobiology, Neuroscience Campus Amsterdam, Center for Neurogenomics and Cognitive Research, Faculty of Earth and Life Sciences, VU University, 1081 HV Amsterdam, The Netherlands
| | - Jamie Peters
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA.
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