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Algallal HE, Jacquemet V, Samaha AN. Intermittent nicotine access is as effective as continuous access in promoting nicotine seeking and taking in rats. Psychopharmacology (Berl) 2024; 241:1135-1149. [PMID: 38326505 DOI: 10.1007/s00213-024-06546-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 01/20/2024] [Indexed: 02/09/2024]
Abstract
RATIONALE Nicotine is a principal psychoactive agent in tobacco, contributing to tobacco's addictive potential. Preclinical studies on the effects of voluntary nicotine intake typically use self-administration procedures that provide continuous nicotine access during each self-administration session. However, many smokers consume cigarettes intermittently rather than continuously throughout each day. For drugs including cocaine and opioids, research in laboratory rats shows that intermittent intake can be more effective than continuous intake in producing patterns of drug use relevant to addiction. OBJECTIVE We determined how intermittent versus continuous nicotine self-administration influences nicotine seeking and taking behaviours. METHODS Female and male rats had continuous (i.e., Long Access; LgA, 6 h/day) or intermittent (IntA; 12 min ON, 60 min OFF, for 6 h/day) access to intravenous nicotine (15 µg/kg/infusion), for 12 daily sessions. We then assessed intake, responding for nicotine under a progressive ratio schedule of drug reinforcement and cue- and nicotine-induced reinstatement of drug seeking. We also estimated nicotine pharmacokinetic parameters during LgA and IntA self-administration. RESULTS Overall, LgA rats took twice more nicotine than did IntA rats, yielding more sustained increases in estimated brain concentrations of the drug. However, the two groups showed similar motivation to seek and take nicotine, as measured using reinstatement and progressive ratio procedures, respectively. CONCLUSIONS Intermittent nicotine use is just as effective as continuous use in producing addiction-relevant behaviours, despite significantly less nicotine exposure. This has implications for modeling nicotine self-administration patterns in human smokers and resulting effects on brain and behaviour.
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Affiliation(s)
- Hajer E Algallal
- Biomedical Sciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Vincent Jacquemet
- Institute of Biomedical Engineering, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada.
- Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montreal, QC, Canada.
- Center for Interdisciplinary Research On the Brain and Learning (CIRCA), Université de Montréal, Montreal, QC, Canada.
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2
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Ndiaye NA, Shamleh SA, Casale D, Castaneda-Ouellet S, Laplante I, Robinson MJF, Samaha AN. Relapse after intermittent access to cocaine: Discriminative cues more effectively trigger drug seeking than do conditioned cues. Psychopharmacology (Berl) 2024:10.1007/s00213-024-06614-9. [PMID: 38767684 DOI: 10.1007/s00213-024-06614-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 05/12/2024] [Indexed: 05/22/2024]
Abstract
RATIONALE When people with drug addiction encounter cues associated with drug use, this can trigger cravings and relapse. These cues can include conditioned stimuli (CSs) signaling drug delivery and discriminative stimuli (DSs) signaling drug availability. Compared to CS effects, DS effects are less explored in preclinical studies on cue-induced relapse. OBJECTIVE We compared CS and DS effects on reward seeking following abstinence from intermittent-access cocaine (or sucrose) self-administration. METHODS During 15-20 intermittent-access sessions, rats self-administered i.v. cocaine or sucrose pellets paired with a light-tone CS. Cocaine/sucrose was available for 5-min (signalled by a light; DS+) and unavailable for 25 min (signalled by different lighting conditions; DS-), and this cycled for 4 h/session. Following abstinence, we measured cocaine/sucrose seeking under extinction triggered by CS and DS presentation, and instrumental responding reinforced by these cues. RESULTS Across intermittent-access sessions, rats increased lever pressing for cocaine or sucrose during DS+ periods and decreased responding during DS- periods. On days 2 and 21 of abstinence, only presentation of the DS+ or DS+ and CS combined elicited increased cocaine/sucrose-seeking behaviour (i.e., increased active lever presses). Presenting the DS- alongside the DS+ suppressed the increased cocaine-seeking behaviour otherwise produced by the DS+ . Finally, on day 21 of abstinence, rats showed equivalent levels of lever pressing reinforced by the DS+ , CS and by the DS+ and CS combined, suggesting comparable conditioned reinforcing value. CONCLUSIONS After intermittent self-administration, cocaine-associated DSs and CSs acquire similar conditioned reinforcing properties, but DSs more effectively trigger increases in drug seeking.
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Affiliation(s)
- Ndeye Aissatou Ndiaye
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Sema Abu Shamleh
- Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada
| | - Domiziana Casale
- Department of Psychology, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | | | - Isabel Laplante
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Mike J F Robinson
- Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville Montréal, Montréal, Québec, H3C 3J7, Canada.
- Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
- Center for Interdisciplinary Research On the Brain and Learning (CIRCA), Université de Montréal, Montréal, QC, H3C 3J7, Canada.
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montréal, QC, H3G 1M8, Canada.
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Namba MD, Xie Q, Park K, Jackson JG, Barker JM. EcoHIV Infection Modulates the Effects of Cocaine Exposure Pattern and Abstinence on Cocaine Seeking and Neuroimmune Protein Expression in Male Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.15.589615. [PMID: 38659915 PMCID: PMC11042347 DOI: 10.1101/2024.04.15.589615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Cocaine use disorders (CUDs) and human immunodeficiency virus (HIV) remain persistent public health dilemmas throughout the world. One major hurdle for treating CUD is the increase in cocaine craving and seeking behavior that occurs over a protracted period of abstinence, an effect known as the incubation of craving. Little is known about how HIV may modulate this process. Thus, we sought to examine the impact of chronic HIV infection on the incubation of cocaine craving and associated changes in the central and peripheral immune systems. Here, mice were inoculated with EcoHIV, which is a chimeric HIV-1 construct that produces chronic HIV infection in mice. EcoHIV- and sham-infected mice were conditioned with cocaine daily or intermittently in a conditioned place preference (CPP) paradigm, followed by 1 or 21 days of forced abstinence prior to assessing preference for the cocaine-paired chamber. Under both conditioning regimens, sham mice exhibited incubation of cocaine CPP after 21 days of abstinence. EcoHIV-infected mice conditioned daily with cocaine showed enhanced cocaine seeking at both abstinence timepoints, whereas infected mice conditioned intermittently showed a reversal of the incubation effect, with higher cocaine seeking after 1 day of abstinence compared to 21 days. Analysis of corticolimbic CX3CL1-CX3CR1 and glutamate receptor expression revealed alterations in medial prefrontal cortex (mPFC) CX3CL1 and nucleus accumbens (NAc) GluN2A receptors that correlated with cocaine seeking following daily cocaine exposure. Moreover, examination of peripheral immune markers showed that the effect of abstinence and EcoHIV infection on these measures depended on the cocaine exposure regimen. Altogether, these results highlight the importance of cocaine abstinence and exposure pattern as critical variables that modulate HIV-associated neuroimmune outcomes and relapse vulnerability.
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Affiliation(s)
- Mark D. Namba
- Department of Pharmacology & Physiology, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Qiaowei Xie
- Department of Pharmacology & Physiology, College of Medicine, Drexel University, Philadelphia, PA, USA
- Graduate Program in Pharmacology and Physiology, College of Medicine, Drexel University
| | - Kyewon Park
- Center for AIDS Research (CFAR), University of Pennsylvania, Philadelphia, PA, USA
| | - Joshua G. Jackson
- Department of Pharmacology & Physiology, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Jacqueline M. Barker
- Department of Pharmacology & Physiology, College of Medicine, Drexel University, Philadelphia, PA, USA
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4
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Doyle MR, Beltran NM, Bushnell MSA, Syed M, Acosta V, Desai M, Rice KC, Serafine KM, Gould GG, Daws LC, Collins GT. Effects of access condition on substance use disorder-like phenotypes in male and female rats self-administering MDPV or cocaine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583431. [PMID: 38496609 PMCID: PMC10942381 DOI: 10.1101/2024.03.04.583431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Substance use disorder (SUD) is a heterogeneous disorder, where severity, symptoms, and patterns of substance use vary across individuals. Yet, when rats are allowed to self-administer drugs such as cocaine under short-access conditions, their behavior tends to be well-regulated and homogeneous in nature; though individual differences can emerge when rats are provided long- or intermittent-access to cocaine. In contrast to cocaine, significant individual differences emerge when rats are allowed to self-administer 3,4-methylenedioxypyrovalerone (MDPV), even under short-access conditions, wherein ~30% of rats rapidly transition to high levels of drug-taking. This study assessed the SUD-like phenotypes of male and female Sprague Dawley rats self-administering MDPV (0.032 mg/kg/infusion) or cocaine (0.32 mg/kg/infusion) by comparing level of drug intake, responding during periods of signaled drug unavailability, and sensitivity to footshock punishment to test the hypotheses that: (1) under short-access conditions, rats that self-administer MDPV will exhibit a more robust SUD-like phenotype than rats that self-administered cocaine; (2) female rats will have a more severe phenotype than male rats; and (3) compared to short-access, long- and intermittent-access to MDPV or cocaine self-administration will result in a more robust SUD-like phenotype. After short-access, rats that self-administered MDPV exhibited a more severe phenotype than rats that self-administered cocaine. Though long- and intermittent-access to cocaine and MDPV self-administration altered drug-taking patterns, manipulating access conditions did not systematically alter their SUD-like phenotype. Evidence from behavioral and quantitative autoradiography studies suggest that these differences are unlikely due to changes in expression levels of dopamine transporter, dopamine D2 or D3 receptors, or 5-HT1B, 5-HT2A, or 5-HT2C receptors, though these possibilities cannot be ruled out. These results show that the phenotype exhibited by rats self-administering MDPV differs from that observed for rats self-administering cocaine, and suggests that individuals that use MDPV and/or related cathinones may be at greater risk for developing a SUD, and that short-access MDPV self-administration may provide a useful method to understand the factors that mediate the transition to problematic or disordered substance use in humans.
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Affiliation(s)
- Michelle R. Doyle
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Nina M. Beltran
- Department of Psychology, University of Texas at El Paso, El Paso, TX, USA
| | - Mark S. A. Bushnell
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Maaz Syed
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Valeria Acosta
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Marisa Desai
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Kenner C. Rice
- Drug Design and Synthesis Section, Molecular Targets and Medications Discovery Branch National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism - Intramural Research Program, Bethesda, MD
| | | | - Georgianna G. Gould
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Lynette C. Daws
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Gregory T. Collins
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- South Texas Veterans Health Care System, San Antonio, TX, USA
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Beasley MM, Pilz EM, Kearns DN. A test of the role of stimulus-response and stimulus-outcome associations in the effects of intermittent-access training. Behav Processes 2024; 214:104984. [PMID: 38103808 PMCID: PMC10842382 DOI: 10.1016/j.beproc.2023.104984] [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: 07/25/2023] [Revised: 10/24/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023]
Abstract
Increased reinforcer motivation in rats has been repeatedly demonstrated following intermittent-access (IntA) training, where the reinforcer is only available for brief periods during a session, compared to continuous-access (ContA) training where the reinforcer is available throughout the session. The present study investigated whether different associations learned during training on the two procedures contributes to the effect. Two experiments tested the importance of the stimulus-response (S-R) and stimulus-outcome (S-O) associations between the IntA availability cues and the training response and reinforcer, respectively. In Exp. 1, separate groups of rats were trained to lever press for saccharin on the IntA or ContA procedures. Increased motivation for saccharin was observed in the IntA group on a later progressive ratio test where nosepoking was the operant (but not when lever pressing was the operant). The outcome of the nosepoke test suggests that a potential S-R association formed during IntA training was not critical for the effect. In Exp. 2, increased saccharin motivation (on nosepoke tests) after IntA training (with lever pressing) was observed regardless of the presence or absence of IntA availability cues, indicating that the S-O association formed during training is not critical for the effect either. Overall, these results suggest that the elemental associations learned on IntA procedures may not be what drives increased motivation observed after IntA training.
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Affiliation(s)
- Madeline M Beasley
- Psychology Department, American University, Washington, DC, United States
| | - Emma M Pilz
- Psychology Department, American University, Washington, DC, United States
| | - David N Kearns
- Psychology Department, American University, Washington, DC, United States.
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6
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Robinson MJF, Bonmariage QSA, Samaha AN. Unpredictable, intermittent access to sucrose or water promotes increased reward pursuit in rats. Behav Brain Res 2023; 453:114612. [PMID: 37544370 DOI: 10.1016/j.bbr.2023.114612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/18/2023] [Accepted: 08/02/2023] [Indexed: 08/08/2023]
Abstract
Reward uncertainty can sensitize reward pathways, promoting increased reward-seeking and -taking behaviours. This is relevant to human conditions such as pathological gambling, eating disorders and drug addiction. In the context of addiction, preclinical self-administration procedures have been developed to model the intermittency of human drug use. These intermittent-access (IntA) procedures involve intermittent but predictable access to drug during self-administration sessions. However, human drug use typically involves intermittent and unpredictable drug access. We introduce a new procedure modeling unpredictable, intermittent access (UIntA) to a reinforcer, and we compare it to procedures that provide predictable reinforcer availability; continuous (ContA) or intermittent (IntA) access. Female rats self-administered water or liquid sucrose in daily hour-long sessions. IntA and ContA rats had access to a fixed volume of water or sucrose (0.1 ml), under a fixed ratio 3 schedule of reinforcement. IntA rats had predictable 5-min reinforcer ON and 25-min reinforcer OFF periods. ContA rats had 60 min of reinforcer access during each session. For UIntA rats, variation in the length of ON and OFF periods (1, 5 or 9 min/period), response requirement (variable ratio 3 schedule of reinforcement), reinforcer probability (50%) and quantity (0, 0.1 or 0.2 ml) introduced reward uncertainty. Following 14 daily self-administration sessions, UIntA rats showed the highest levels of responding for water or sucrose under progressive ratio conditions, responding under extinction conditions, and cue-induced reinstatement of sucrose seeking. Thus, unpredictable, intermittent reward access promotes increased reward pursuit. This has implications for modeling addiction and other disorders of increased reward seeking.
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Affiliation(s)
- Mike J F Robinson
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Qi Shan A Bonmariage
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada; Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada; Center for Interdisciplinary Research on the Brain and Learning (CIRCA), Université de Montréal, Montréal, QC H3T 1J4, Canada; Neuroscience and Mental Health Strategy of the Université de Montréal (SENSUM), Université de Montréal, Montréal, QC H3T 1J4, Canada.
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7
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Bender BN, Torregrossa MM. Intermittent cocaine self-administration has sex-specific effects on addiction-like behaviors in rats. Neuropharmacology 2023; 230:109490. [PMID: 36889433 PMCID: PMC10040443 DOI: 10.1016/j.neuropharm.2023.109490] [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: 12/19/2022] [Revised: 02/21/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023]
Abstract
Intermittent access (IntA) models of cocaine self-administration were developed to better model in rodents how cocaine is used by human drug users. Compared to traditional continuous access (ContA) models, IntA has been shown to enhance several pharmacological and behavioral effects of cocaine, but few studies have examined sex differences in IntA. Moreover, no one has examined the efficacy of cue extinction to reduce cocaine seeking in the IntA model, which has previously shown to be ineffective in other models that promote habit-like cocaine seeking. Therefore, rats were implanted with jugular vein catheters and dorsolateral striatum (DLS) cannulae and trained to self-administer cocaine paired with an audiovisual cue with ContA or IntA. In subsets of rats, we evaluated: the ability of Pavlovian cue extinction to reduce cue-induced drug seeking; motivation for cocaine using a progressive ratio procedure; punishment-resistant cocaine taking by pairing cocaine infusions with footshocks; and dependence of drug-seeking on DLS dopamine (a measure of habit-like behavior) with the dopamine antagonist cis-flupenthixol. Overall, cue extinction reduced cue-induced drug seeking after ContA or IntA. Compared to ContA, IntA resulted in increased motivation for cocaine exclusively in females, but IntA facilitated punished cocaine self-administration exclusively in males. After 10 days of IntA training, but not fewer, drug-seeking was dependent on DLS dopamine most notably in males. Our results suggest that IntA may be valuable for identifying sex differences in the early stages of drug use and provide a foundation for the investigation of the mechanisms involved.
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Affiliation(s)
- Brooke N Bender
- Department of Psychiatry, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA, 15219, USA; Center for Neuroscience, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA, 15213, USA
| | - Mary M Torregrossa
- Department of Psychiatry, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA, 15219, USA; Center for Neuroscience, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA, 15213, USA.
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Gage GA, Muench MA, Jee C, Kearns DN, Chen H, Tunstall BJ. Intermittent-access operant alcohol self-administration promotes binge-like drinking and drinking despite negative consequences in male and female heterogeneous stock rats. Neuropharmacology 2023; 235:109564. [PMID: 37149215 DOI: 10.1016/j.neuropharm.2023.109564] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 04/22/2023] [Accepted: 04/25/2023] [Indexed: 05/08/2023]
Abstract
The study of Alcohol Use Disorders (AUD) in preclinical models is hampered by difficulty in training rodents to voluntarily consume high levels of alcohol. The intermittency of alcohol access/exposure is well known to modulate alcohol consumption (e.g., alcohol deprivation effect, intermittent-access two-bottle-choice) and recently, intermittent access operant self-administration procedures have been used to produce more intense and binge-like self-administration of intravenous psychostimulant and opioid drugs. In the present study, we sought to systematically manipulate the intermittency of operant self-administered alcohol access to determine the feasibility of promoting more intensified, binge-like alcohol consumption. To this end, 24 male and 23 female NIH Heterogeneous Stock rats were trained to self-administer 10% w/v ethanol, before being split into three different-access groups. Short Access (ShA) rats continued receiving 30-min training sessions, Long Access (LgA) rats received 16-h sessions, and Intermittent Access (IntA) rats received 16-h sessions, wherein the hourly alcohol-access periods were shortened over sessions, down to 2 min. IntA rats demonstrated an increasingly binge-like pattern of alcohol drinking in response to restriction of alcohol access, while ShA and LgA rats maintained stable intake. All groups were tested on orthogonal measures of alcohol-seeking and quinine-punished alcohol drinking. The IntA rats displayed the most punishment-resistant drinking. In a separate experiment, we replicated our main finding, that intermittent access promotes a more binge-like pattern of alcohol self-administration using 8 male and 8 female Wistar rats. In conclusion, intermittent access to self-administered alcohol promotes more intensified self-administration. This approach may be useful in developing preclinical models of binge-like alcohol consumption in AUD.
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Affiliation(s)
- Grey A Gage
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Marissa A Muench
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Changhoon Jee
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - David N Kearns
- Psychology Department, American University, Washington, DC, USA
| | - Hao Chen
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Brendan J Tunstall
- Department of Pharmacology, Addiction Science and Toxicology, University of Tennessee Health Science Center, Memphis, TN, USA.
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9
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Engineered highs: Reward variability and frequency as potential prerequisites of behavioural addiction. Addict Behav 2023; 140:107626. [PMID: 36701907 DOI: 10.1016/j.addbeh.2023.107626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 12/20/2022] [Accepted: 01/18/2023] [Indexed: 01/22/2023]
Abstract
Influential learning-based accounts of substance addictions posit the attribution of incentive salience to drug-associated cues, and its escalation by the direct dopaminergic effects of drugs. In translating this account to disordered gambling, we have noted how the intermittent nature of monetary rewards in gambling (i.e. the variable ratio) may allow for analogous learning processes, via effects on dopaminergic signalling. The aim of the present article is to consider how multiple sources of reward variability operate within modern gambling products, and how similar sources of variability, as well as some novel sources of variability, also apply to other digital products implicated in behavioural addictions, including gaming, shopping, social media and online pornography. Online access to these activities facilitates not only unparalleled accessibility but also introduces novel forms of reward variability, as seen in the effects of infinite scrolls and personalized recommendations. We use the term uncertainty to refer to the subjective experience of reward variability. We further highlight two psychological factors that appear to moderate the effects of uncertainty: 1) the timecourse of uncertainty, especially with regard to its resolution, 2) the frequency of exposure, allowing temporal compression. Collectively, the evidence illustrates how qualitative and quantitative variability of reward can confer addictive potential to non-drug reinforcers by exploiting the psychological and neural processes that rely on predictability to guide reward seeking behaviour.
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Khoo SYS, Samaha AN. Metabotropic glutamate group II receptor activation in the ventrolateral dorsal striatum suppresses incentive motivation for cocaine in rats. Psychopharmacology (Berl) 2023; 240:1247-1260. [PMID: 37060471 DOI: 10.1007/s00213-023-06363-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 04/03/2023] [Indexed: 04/16/2023]
Abstract
RATIONALE After a history of intermittent cocaine intake, rats develop patterns of drug use characteristic of substance use disorder. The dorsal striatum is involved in the increased pursuit of cocaine after intermittent drug self-administration experience. Within the dorsal striatum, chronic cocaine use changes metabotropic glutamate type II receptor (mGlu2/3) density and function. OBJECTIVES We examined the extent to which activity at Glu2/3 receptors mediates responding for cocaine after intermittent cocaine use. METHODS Male (n = 11) and female (n = 10) Wistar rats self-administered 0.25 mg/kg/infusion cocaine during 10 daily intermittent access (IntA) sessions (5 min ON/25 min OFF, for 5 h/session). We then examined the effects of microinjections of the mGlu2/3 receptor agonist LY379268 (0, 1, and 3 µg/hemisphere) into the ventrolateral part of the dorsal striatum on cocaine self-administration under a progressive ratio schedule of reinforcement. RESULTS Across 10 IntA sessions, the sexes showed similar levels of cocaine intake. In females only, locomotion significantly increased over sessions, suggesting that female rats developed psychomotor sensitization to self-administered cocaine. After 10 IntA sessions, intra-dorsal striatum LY379268 significantly reduced breakpoints achieved for cocaine, active lever presses, and cocaine infusions earned under progressive ratio. LY379268 had no effects on locomotion or inactive lever presses, indicating no motor effects. CONCLUSIONS These results suggest that mGlu2/3 receptor activation in the ventrolateral dorsal striatum suppresses incentive motivation for cocaine, and this holds promise for new treatments to manage substance use disorder.
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Affiliation(s)
- Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada
- Conduct and Integrity Office, Division of Planning and Assurance, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
- Research Group on Neural Signaling and Circuits, Faculty of Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
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Beasley MM, Tunstall BJ, Kearns DN. Intermittent access cocaine self-administration produces context-specific escalation and increased motivation. Drug Alcohol Depend 2023; 245:109797. [PMID: 36801708 PMCID: PMC10033440 DOI: 10.1016/j.drugalcdep.2023.109797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/27/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023]
Abstract
The intermittent-access (IntA) self-administration procedure has been reported to produce intensified addiction-like behavior compared to continuous-access (ContA) procedures. In a common variation of the IntA procedure, cocaine is available for 5 min at the beginning of each half hour of a 6-h session. In contrast, during ContA procedures, cocaine is available continuously throughout a session, typically lasting one or more hours. Previous studies comparing procedures have used between-subjects designs, where separate groups of rats self-administer cocaine on either IntA or ContA procedures. The present study used a within-subjects design where subjects self-administered cocaine on the IntA procedure in one context and self-administered cocaine on the continuous short-access (ShA) procedure in another context during separate sessions. Across sessions, rats escalated cocaine intake in the IntA, but not ShA, context. Following sessions eight and 11, rats were administered a progressive ratio test in each context to monitor the change in cocaine motivation. Rats obtained more cocaine infusions on the progressive ratio test in the IntA context than in the ShA context following 11 sessions. These results suggest that addiction-like behaviors following IntA self-administration may be influenced by context-specific learning factors.
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Affiliation(s)
| | - Brendan J Tunstall
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - David N Kearns
- Psychology Department, American University, Washington, DC, USA
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12
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Saraswat AA, Longyear LG, Kawa AB, Ferrario CR. Cocaine-induced plasticity, motivation, and cue responsivity do not differ in obesity-prone vs obesity-resistant rats; implications for food addiction. Psychopharmacology (Berl) 2023; 240:853-870. [PMID: 36806961 PMCID: PMC10006066 DOI: 10.1007/s00213-023-06327-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/25/2023] [Indexed: 02/20/2023]
Abstract
RATIONALE Compared to obesity-resistant rats, obesity-prone rats consume more food, work harder to obtain food, show greater motivational responses to food-cues, and show greater striatal plasticity in response to eating sugary/fatty foods. Therefore, it is possible that obesity-prone rats may also be more sensitive to the motivational properties of cocaine and cocaine-paired cues, and to plasticity induced by cocaine. OBJECTIVE To examine baseline differences in motivation for cocaine and effects of intermittent access (IntA) cocaine self-administration on cocaine motivation, neurobehavioral responsivity to cocaine-paired cues, and locomotor sensitization in male obesity-prone vs obesity-resistant rats. METHODS Intravenous cocaine self-administration was used to examine drug-taking and drug-seeking in males. Motivation for cocaine was measured using a within session threshold procedure. Cue-induced c-Fos expression in mesocorticolimbic regions was measured. RESULTS Drug-taking and drug-seeking, cue-induced c-Fos, locomotor sensitization, and preferred level of cocaine consumption (Q0) were similar between obesity-prone and obesity-resistant groups. Maximal responding during demand testing (Rmax) was lower in obesity-prone rats. IntA experience enhanced motivation for cocaine (Pmax) in obesity-prone rats. CONCLUSIONS The results do not support robust inherent differences in motivation for cocaine, cue-induced cocaine seeking, or neurobehavioral plasticity induced by IntA in obesity-prone vs obesity-resistant rats. This contrasts with previously established differences seen for food and food cues in these populations and shows that inherent enhancements in motivation for food and food-paired cues do not necessarily transfer to drugs and drug-paired cues.
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Affiliation(s)
- Anish A Saraswat
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109, USA
- Psychology Department (Biopsychology), University of Michigan, Ann Arbor, MI, 48109, USA
| | - Lauren G Longyear
- Psychology Department (Biopsychology), University of Michigan, Ann Arbor, MI, 48109, USA
| | - Alex B Kawa
- Psychology Department (Biopsychology), University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Carrie R Ferrario
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109, USA.
- Psychology Department (Biopsychology), University of Michigan, Ann Arbor, MI, 48109, USA.
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13
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D'Ottavio G, Reverte I, Ragozzino D, Meringolo M, Milella MS, Boix F, Venniro M, Badiani A, Caprioli D. Increased heroin intake and relapse vulnerability in intermittent relative to continuous self-administration: Sex differences in rats. Br J Pharmacol 2023; 180:910-926. [PMID: 34986504 PMCID: PMC9253203 DOI: 10.1111/bph.15791] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 12/02/2021] [Accepted: 12/29/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Studies using intermittent-access drug self-administration show increased motivation to take and seek cocaine and fentanyl, relative to continuous access. In this study, we examined the effects of intermittent- and continuous-access self-administration on heroin intake, patterns of self-administration and cue-induced heroin-seeking, after forced or voluntary abstinence, in male and female rats. We also modelled brain levels of heroin and its active metabolites. EXPERIMENTAL APPROACH Rats were trained to self-administer a palatable solution and then heroin (0.075 mg·kg-1 per inf) either continuously (6 h·day-1 ; 10 days) or intermittently (6 h·day-1 ; 5-min access every 30-min; 10 days). Brain levels of heroin and its metabolites were modelled using a pharmacokinetic software. Next, heroin-seeking was assessed after 1 or 21 abstinence days. Between tests, rats underwent either forced or voluntary abstinence. The oestrous cycle was measured using a vaginal smear test. KEY RESULTS Intermittent access exacerbated heroin self-administration and was characterized by a burst-like intake, yielding higher brain peaks of heroin and 6-monoacetylmorphine concentrations. Moreover, intermittent access increased cue-induced heroin-seeking during early, but not late abstinence. Heroin-seeking was higher in females after intermittent, but not continuous access, and this effect was independent of the oestrous cycle. CONCLUSIONS AND IMPLICATIONS Intermittent heroin access in rats resembles critical features of heroin use disorder: a self-administration pattern characterized by repeated large doses of heroin and higher relapse vulnerability during early abstinence. This has significant implications for refining animal models of substance use disorder and for better understanding of the neuroadaptations responsible for this disorder. LINKED ARTICLES This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.
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Affiliation(s)
- Ginevra D'Ottavio
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy
| | - Ingrid Reverte
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy
| | - Davide Ragozzino
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy
| | - Maria Meringolo
- Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy
| | - Michele Stanislaw Milella
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Toxicology Unit, Policlinico Umberto I University Hospital, Rome, Italy
| | - Fernando Boix
- Section for Drug Abuse Research, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
| | - Marco Venniro
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Aldo Badiani
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Sussex Addiction Research and Intervention Centre (SARIC) and School of Psychology, University of Sussex, Brighton, UK
| | - Daniele Caprioli
- Laboratory affiliated to Institute Pasteur Italia - Fondazione Cenci Bolognetti - Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy
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14
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Bailey LS, Bagley JR, Wherry JD, Chesler EJ, Karkhanis A, Jentsch JD, Tarantino LM. Repeated dosing with cocaine produces strain-dependent effects on responding for conditioned reinforcement in Collaborative Cross mice. Psychopharmacology (Berl) 2023; 240:561-573. [PMID: 36239767 PMCID: PMC10083021 DOI: 10.1007/s00213-022-06256-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 10/02/2022] [Indexed: 11/24/2022]
Abstract
RATIONALE Cocaine use disorder (CUD) is a highly heritable form of substance use disorder, with genetic variation accounting for a substantial proportion of the risk for transitioning from recreational use to a clinically impairing addiction. With repeated exposures to cocaine, psychomotor and incentive sensitization are observed in rodents. These phenomena are thought to model behavioral changes elicited by the drug that contribute to the progression into addiction, but little is known about how genetic variation may moderate these consequences. OBJECTIVES Here, we describe the use of two Collaborative Cross (CC) recombinant inbred mouse strains that either exhibit high (CC018/UncJ) or no (CC027/GeniUncJ) psychomotor sensitization in response to cocaine to measure phenotypes related to incentive sensitization after repeated cocaine exposures; given the relationship of incentive motivation to nucleus accumbens core (NAc) dopamine release and reuptake, we also assessed these neurochemical mechanisms. METHODS Adult male and female CC018/UncJ and CC027/GeniUncJ mice underwent Pavlovian conditioning to associate a visual cue with presentation of a palatable food reward, then received five, every-other-day injections of cocaine or vehicle. Following Pavlovian re-training, they underwent testing acquisition of a new operant response for the visual cue, now serving as a conditioned reinforcer. Subsequently, electrically evoked dopamine release was assessed using fast-scan cyclic voltammetry from acute brain slices containing the NAc. RESULTS While both strains acquired the Pavlovian association, only CC018/UncJ mice showed conditioned reinforcement and incentive sensitization in response to cocaine, while CC027/GeniUncJ mice did not. Voltammetry data revealed that CC018/UncJ, compared to CC027/GeniUnc, mice exhibited higher baseline dopamine release and uptake. Moreover, chronic cocaine exposure blunted tonic and phasic dopamine release in CC018/UncJ, but not CC027/GeniUncJ, mice. CONCLUSIONS Genetic background is a moderator of cocaine-induced neuroadaptations in mesolimbic dopamine signaling, which may contribute to both psychomotor and incentive sensitization and indicate a shared biological mechanism of variation.
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Affiliation(s)
- Lauren S Bailey
- Department of Psychology, State University of New York - Binghamton University, PO Box 6000, Binghamton, NY, 13902-6000, USA
| | - Jared R Bagley
- Department of Psychology, State University of New York - Binghamton University, PO Box 6000, Binghamton, NY, 13902-6000, USA
| | - James D Wherry
- Department of Psychology, State University of New York - Binghamton University, PO Box 6000, Binghamton, NY, 13902-6000, USA
| | | | - Anushree Karkhanis
- Department of Psychology, State University of New York - Binghamton University, PO Box 6000, Binghamton, NY, 13902-6000, USA
| | - James D Jentsch
- Department of Psychology, State University of New York - Binghamton University, PO Box 6000, Binghamton, NY, 13902-6000, USA.
- The Jackson Laboratory, Bar Harbor, ME, USA.
| | - Lisa M Tarantino
- The Jackson Laboratory, Bar Harbor, ME, USA
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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15
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Collins V, Bornhoft KN, Wolff A, Sinha S, Saunders BT. Hierarchical cue control of cocaine seeking in the face of cost. Psychopharmacology (Berl) 2023; 240:461-476. [PMID: 36069951 PMCID: PMC10131580 DOI: 10.1007/s00213-022-06218-1] [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: 05/04/2022] [Accepted: 08/22/2022] [Indexed: 12/30/2022]
Abstract
RATIONALE Addiction is characterized by intermittent drug seeking despite rising costs. This behavior is heavily influenced by environmental stimuli that signal drug availability and reinforce drug seeking. OBJECTIVE To establish the relationship between three key aspects of human drug use in rats: the intermittent, binge nature of drug intake, the motivational conflict of drug seeking in the face of escalating negative costs, and the ability of different drug cues to interact to modulate relapse. METHODS Male and female rats were trained to self-administer cocaine on an intermittent access schedule, where brief drug-availability states were signaled by a shift in the ambient lighting of the environment, and cocaine infusions were signaled by a separate proximal discrete cue. Rats then went through a conflict procedure, where foot shock intensity associated with cocaine seeking was escalated until intake was suppressed. We then completed relapse tests where the drug-delivery cue was noncontingently presented alone, or in the context of dynamic drug-availability state transitions. RESULTS Intermittent access spurred psychomotor sensitization and binge-like cocaine intake. The intensity of binge-like drug taking during training was predictive of later drug seeking despite escalating costs during conflict. In relapse tests, the ability of a proximal discrete drug cue to trigger relapse was gated by the presence of a global cue signaling drug-availability state transitions. CONCLUSIONS Our results suggest that the pattern of drug intake plays a role in many features of addiction, including modifying an individual's willingness to endure high costs associated with drug seeking. Furthermore, our studies indicate that drug-related sensory information can be hierarchically organized to exert a dynamic modulating influence on drug-seeking motivation.
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Affiliation(s)
- Val Collins
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Medical Discovery Team On Addiction, University of Minnesota, Minneapolis, MN, USA
- University of California, San Francisco, CA, USA
| | - Kaisa N Bornhoft
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Medical Discovery Team On Addiction, University of Minnesota, Minneapolis, MN, USA
| | - Amy Wolff
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Medical Discovery Team On Addiction, University of Minnesota, Minneapolis, MN, USA
| | - Sonal Sinha
- Johns Hopkins University, Baltimore, MD, USA
| | - Benjamin T Saunders
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA.
- Medical Discovery Team On Addiction, University of Minnesota, Minneapolis, MN, USA.
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16
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Cippitelli A, Zribi G, Toll L. PPL-103: A mixed opioid partial agonist with desirable anti-cocaine properties. Prog Neuropsychopharmacol Biol Psychiatry 2022; 119:110599. [PMID: 35798174 DOI: 10.1016/j.pnpbp.2022.110599] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 11/19/2022]
Abstract
Cocaine use disorder (CUD) is a persistent public health problem for which no effective medications are available. PPL-103 is an opioid receptor ligand with partial agonist activity at mu, kappa and delta opioid receptors, with a greater efficacy for kappa and low efficacy at mu receptors. Because chronic cocaine use induces changes in the kappa opioid receptor/dynorphin system, we hypothesized that a kappa partial agonist, such as PPL-103, would attenuate the aversive properties of the upregulated kappa system, resulting in effective treatment approach for CUD. We tested the effects of PPL-103 on cocaine self-administration models that recapitulate core aspects of CUD in humans. We found that PPL-103 reduced both long and short access cocaine self-administration, motivation to respond for cocaine, and binge-like cocaine taking, in rats. Operant responding for food, fentanyl and locomotor behavior were not altered at doses that decreased cocaine infusions. Repeated PPL-103 treatment did not lead to tolerance development. PPL-103 also reduced both priming- and cue-induced reinstatement of cocaine seeking, being more effective in the former. Surprisingly, PPL-103 reduced self-administration parameters and reinstatement in rats previously treated with the long-acting kappa receptor antagonist JDTic more potently than in non-JDTic treated animals, whereas naltrexone injected to rats subsequent to JDTic administration increased self-administration, suggesting that the partial mu agonist activity, rather than kappa agonism is important for reduction in cocaine taking and seeking. However, partial kappa activation seems to increase safety by limiting dysphoria, tolerance and addiction development. PPL-103 displays a desirable profile as a possible CUD pharmacotherapy.
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Affiliation(s)
- Andrea Cippitelli
- Biomedical Science Department, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States.
| | - Gilles Zribi
- Biomedical Science Department, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States
| | - Lawrence Toll
- Biomedical Science Department, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States
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17
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Beasley MM, Gunawan T, Tunstall BJ, Kearns DN. Intermittent access training produces greater motivation for a non-drug reinforcer than long access training. Learn Behav 2022; 50:509-523. [PMID: 35132517 PMCID: PMC10237344 DOI: 10.3758/s13420-022-00512-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2022] [Indexed: 01/01/2023]
Abstract
It has recently been proposed that the intermittent access (IntA) drug self-administration procedure better produces behavioral changes relevant to addiction than the long access (LgA) procedure. In this version of the IntA procedure, the drug is made available for a 5-min period during each half hour of a 6-h session. In contrast, on the LgA procedure, the drug is available continuously for 6 h. Previous studies have found that IntA drug self-administration produces greater drug motivation, measured by increased progressive ratio breakpoints, than LgA self-administration. It has been hypothesized that this effect is due to the rapid, "spiking" brain levels of the drug, and consequent neuroadaptations, experienced by rats during IntA sessions. However, no study has compared the effects of IntA versus LgA training on reinforcer motivation when using a non-drug reinforcer. The present study compared motivation for a saccharin reinforcer after IntA or LgA training. In Experiment 1, separate groups of rats lever-pressed for saccharin on the IntA or LgA procedures. In Experiment 2, a within-subjects design was used where rats pressed one lever on the IntA procedure and another lever on the LgA procedure for saccharin. In both experiments, IntA training produced greater breakpoints than LgA training. As no drug was used here, spiking drug levels could not have been responsible for the increased saccharin motivation observed after IntA training. Instead, it is proposed that differences in stimulus-reinforcer associations learned during IntA versus LgA training may be responsible for the effect. Future research is needed to determine the extent to which such learning factors may contribute to the increased motivation observed after IntA training with drug reinforcers.
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Affiliation(s)
- Madeline M Beasley
- Psychology Department, American University, 4400 Massachusetts Ave NW, Washington, DC, 20016, USA.
| | - Tommy Gunawan
- Human Psychopharmacology Laboratory, NIH/NIAAA, Bethesda, MD, USA
| | - Brendan J Tunstall
- Department of Pharmacology, Addiction Science, and Toxicology, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - David N Kearns
- Psychology Department, American University, 4400 Massachusetts Ave NW, Washington, DC, 20016, USA
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18
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D-amphetamine maintenance therapy reduces cocaine use in female rats. Psychopharmacology (Berl) 2022; 239:3755-3770. [PMID: 36357743 DOI: 10.1007/s00213-022-06271-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 10/19/2022] [Indexed: 11/12/2022]
Abstract
RATIONALE D-amphetamine maintenance therapy is a promising strategy to reduce drug use in cocaine use disorder (addiction). In both male rats and human cocaine users, d-amphetamine treatment reduces cocaine-taking and -seeking. However, this has not been examined systematically in female animals, even though cocaine addiction afflicts both sexes, and the sexes can differ in their response to cocaine. OBJECTIVES We determined how d-amphetamine maintenance therapy during cocaine self-administration influences cocaine use in female rats. METHODS In experiment 1, two groups of female rats received 14 intermittent access (IntA) cocaine self-administration sessions. One group received concomitant d-amphetamine maintenance treatment (COC + A rats; 5 mg/kg/day, via minipump), the other group did not (COC rats). After discontinuing d-amphetamine treatment, we measured responding for cocaine under a progressive ratio schedule, responding under extinction, and cocaine-primed reinstatement of drug-seeking. In experiment 2, we assessed the effects of d-amphetamine maintenance on these measures in already IntA cocaine-experienced rats. Thus, rats first received 14 IntA cocaine self-administration sessions without d-amphetamine. They then received 14 more IntA sessions, now either with (COC/COC + A rats) or without (COC/COC rats) concomitant d-amphetamine treatment. RESULTS In both experiments, d-amphetamine treatment did not significantly influence ongoing cocaine self-administration behaviour. After d-amphetamine treatment cessation, cocaine-primed reinstatement of cocaine-seeking was also unchanged. However, after d-amphetamine treatment cessation, rats responded less for cocaine both under progressive ratio and extinction conditions. CONCLUSIONS D-amphetamine treatment can both prevent and reverse increases in the motivation to take and seek cocaine in female animals.
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19
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Glutamate inputs from the laterodorsal tegmental nucleus to the ventral tegmental area are essential for the induction of cocaine sensitization in male mice. Psychopharmacology (Berl) 2022; 239:3263-3276. [PMID: 36006414 DOI: 10.1007/s00213-022-06209-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/02/2022] [Indexed: 10/15/2022]
Abstract
RATIONALE Drug-induced potentiation of ventral tegmental area (VTA) glutamate signaling contributes critically to the induction of sensitization - an enhancement in responding to a drug following exposure which is thought to reflect neural changes underlying drug addiction. The laterodorsal tegmental nucleus (LDTg) provides one of several sources of glutamate input to the VTA. OBJECTIVE We used optogenetic techniques to test either the role of LDTg glutamate cells or their VTA afferents in the development of cocaine sensitization in male VGluT2::Cre mice. These were inhibited using halorhodopsin during each of five daily cocaine exposure injections. The expression of locomotor sensitization was assessed following a cocaine challenge injection 1-week later. RESULTS The locomotor sensitization seen in control mice was absent in male mice subjected to inhibition of LDTg-VTA glutamatergic circuitry during cocaine exposure. As sensitization of nucleus accumbens (NAcc) dopamine (DA) overflow is also induced by this drug exposure regimen, we used microdialysis to measure NAcc DA overflow on the test for sensitization. Consistent with the locomotor sensitization results, inhibition of LDTg glutamate afferents to the VTA during cocaine exposure prevented the sensitization of NAcc DA overflow observed in control mice. CONCLUSIONS These data identify the LDTg as the source of VTA glutamate critical for the development of cocaine sensitization in male mice. Accordingly, the LDTg may give rise to the synapses in the VTA at which glutamatergic plasticity, known to contribute to the enhancement of addictive behaviors, occurs.
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Alonso IP, O'Connor BM, Bryant KG, Mandalaywala RK, España RA. Incubation of cocaine craving coincides with changes in dopamine terminal neurotransmission. ADDICTION NEUROSCIENCE 2022; 3. [PMID: 36081573 PMCID: PMC9451023 DOI: 10.1016/j.addicn.2022.100029] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Relapse to drug use is one of the major challenges in treating substance use disorders. Exposure to drug-related cues and contexts triggers drug craving, which drives cocaine seeking, and increases the probability of relapse. Clinical and animal studies have shown a progressive intensification of cocaine seeking and craving that develops over the course of abstinence, a phenomenon commonly referred to as incubation of cocaine craving. Although the neurobiology underlying incubation of cocaine craving has been examined – particularly within the context of glutamate plasticity– the extent to which increased cocaine craving engenders mesolimbic dopamine (DA) changes has received relatively little attention. To assess whether incubation of cocaine craving is associated with alterations in DA terminal neurotransmission in the nucleus accumbens core (NAc), we used ex vivo fast scan cyclic voltammetry in female and male rats to assess DA dynamics following short access, long access, or intermittent access to cocaine self-administration followed by 28 days of abstinence. Results indicated that both long access and intermittent access to cocaine produced robust incubation of cocaine craving, which was associated with increases in cocaine potency. In addition, intermittent access self-administration also produced a robust increase in DA uptake rate at baseline. In contrast, short access to cocaine did not engender incubation of cocaine craving, nor produce changes in DA neurotransmission. Together these observations indicate that incubation of cocaine craving coincides with changes in DA transmission, suggesting that underlying changes in mesolimbic DA signaling may contribute to the progressive intensification of drug craving that occurs across periods of abstinence.
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21
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O'Connor RM, Kenny PJ. Utility of 'substance use disorder' as a heuristic for understanding overeating and obesity. Prog Neuropsychopharmacol Biol Psychiatry 2022; 118:110580. [PMID: 35636576 DOI: 10.1016/j.pnpbp.2022.110580] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/24/2022] [Accepted: 05/24/2022] [Indexed: 02/07/2023]
Abstract
Rates of obesity and obesity-associated diseases have increased dramatically in countries with developed economies. Substance use disorders (SUDs) are characterized by the persistent use of the substance despite negative consequences. It has been hypothesized that overconsumption of palatable energy dense food can elicit SUD-like maladaptive behaviors that contribute to persistent caloric intake beyond homeostatic need even in the face of negative consequences. Palatable food and drugs of abuse act on many of the same motivation-related circuits in the brain, and can induce, at least superficially, similar molecular, cellular, and physiological adaptations on these circuits. As such, applying knowledge about the neurobiological mechanisms of SUDs may serve as useful heuristic to better understand the persistent overconsumption of palatable food that contributes to obesity. However, many important differences exist between the actions of drugs of abuse and palatable food in the brain. This warrants caution when attributing weight gain and obesity to the manifestation of a putative SUD-related behavioral disorder. Here, we describe similarities and differences between compulsive drug use in SUDs and overconsumption in obesity and consider the merit of the concept of "food addiction".
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Affiliation(s)
- Richard M O'Connor
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, United States of America
| | - Paul J Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, United States of America.
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22
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Tapia MA, Jin XT, Tucker BR, Thomas LN, Walker NB, Kim VJ, Albertson SE, Damuka N, Krizan I, Edassery S, Savas JN, Sai KKS, Jones SR, Drenan RM. Relapse-like behavior and nAChR sensitization following intermittent access nicotine self-administration. Neuropharmacology 2022; 212:109066. [PMID: 35461879 PMCID: PMC9527938 DOI: 10.1016/j.neuropharm.2022.109066] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/04/2022] [Accepted: 04/17/2022] [Indexed: 11/28/2022]
Abstract
Many tobacco smokers consume nicotine intermittently, but the underlying mechanisms and neurobiological changes associated with intermittent nicotine intake are unclear. Understanding intermittent nicotine intake is a high priority, as it could promote therapeutic strategies to attenuate tobacco consumption. We examined nicotine intake behavior and neurobiological changes in male rats that were trained to self-administer nicotine during brief (5 min) trials interspersed with longer (15 min) drug-free periods. Rats readily adapted to intermittent access (IntA) SA following acquisition on a continuous access (ContA) schedule. Probabilistic analysis of IntA nicotine SA suggested reduced nicotine loading behavior compared to ContA, and nicotine pharmacokinetic modeling revealed that rats taking nicotine intermittently may have increased intake to maintain blood levels of nicotine that are comparable to ContA SA. After IntA nicotine SA, rats exhibited an increase in unreinforced responses for nicotine-associated cues (incubation of craving) and specific alterations in the striatal proteome after 7 days without nicotine. IntA nicotine SA also induced nAChR functional upregulation in the interpeduncular nucleus (IPN), and it enhanced nicotine binding in the brain as determined via [11C]nicotine positron emission tomography. Reducing the saliency of the cue conditions during the 5 min access periods attenuated nicotine intake, but incubation of craving was preserved. Together, these results indicate that IntA conditions promote nicotine SA and nicotine seeking after a nicotine-free period.
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Affiliation(s)
- Melissa A. Tapia
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Xiao-Tao Jin
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Brenton R. Tucker
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Leanne N. Thomas
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Noah B. Walker
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Veronica J. Kim
- Department of Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Steven E. Albertson
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Naresh Damuka
- Department of Radiological Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Ivan Krizan
- Department of Radiological Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Seby Edassery
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Jeffrey N. Savas
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Sara R. Jones
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Ryan M. Drenan
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA,Corresponding author. (R.M. Drenan)
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Johnson AR, Christensen BA, Kelly SJ, Calipari ES. The influence of reinforcement schedule on experience-dependent changes in motivation. J Exp Anal Behav 2022; 117:320-330. [PMID: 35344601 PMCID: PMC9090977 DOI: 10.1002/jeab.755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 12/19/2022]
Abstract
The progressive ratio procedure is used across fields to assess motivation for different reinforcers, define the effects of experimental interventions on motivation, and determine experience-dependent changes in motivation. However, less is known about how operant training schedules affect performance on this widely utilized task. Here we designed an experiment to examine the effect of variable ratio versus fixed ratio training schedules of reinforcement on progressive ratio performance while holding other performance variables constant between groups. We found a robust increase in maximum ratio completed between the pretest and posttraining test highlighting a robust training effect on progressive ratio performance. However, it did not matter if the training was under a fixed or variable ratio schedule. Additionally, we show that neither individual rates during training nor extinction responding correlated with maximum ratio achieved during the sessions. Finally, we show that rates during the training sessions do correlate with extinction performance, suggesting that these variables measure a different aspect of performance that does not predict motivation.
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Affiliation(s)
| | - Brooke A Christensen
- Department of Pharmacology, Vanderbilt University
- Vanderbilt Brain Institute, Vanderbilt University
| | | | - Erin S Calipari
- Department of Pharmacology, Vanderbilt University
- Vanderbilt Brain Institute, Vanderbilt University
- Vanderbilt Center for Addiction Research, Vanderbilt University
- Department of Molecular Physiology and Biophysics, Vanderbilt University
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University
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24
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Venniro M, Panlilio LV, Epstein DH, Shaham Y. The protective effect of operant social reward on cocaine self-administration, choice, and relapse is dependent on delay and effort for the social reward. Neuropsychopharmacology 2021; 46:2350-2357. [PMID: 34400784 PMCID: PMC8580997 DOI: 10.1038/s41386-021-01148-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/28/2021] [Accepted: 08/04/2021] [Indexed: 02/06/2023]
Abstract
Social reinforcement-based treatments are effective for many, but not all, people with addictions to drugs. We recently developed an operant rat model that mimics features of one such treatment, the community-reinforcement approach. In this model, rats uniformly choose social interaction over methamphetamine or heroin. Abstinence induced by social preference protects against the incubation of drug-seeking that would emerge during forced abstinence. Here, we determined whether these findings generalize to cocaine and whether delaying or increasing effort for social interaction could reveal possibly human-relevant individual differences in responsiveness. We trained male and female rats for social self-administration (6 days) and then for cocaine self-administration, initially for 2-h/day for 4 days, and then for 12-h/day continuously or intermittently for 8 days. We assessed relapse to cocaine seeking after 1 and 15 days. Between tests, the rats underwent either forced abstinence or social-choice-induced abstinence. After establishing stable social preference, we manipulated the delay for both rewards or for social reward alone, or the response requirements (effort) for social reward. Independent of cocaine-access conditions and sex, operant social interaction inhibited cocaine self-administration and prevented incubation of cocaine seeking. Preference for social access was decreased by the delay of both rewards or social reward alone, or by increased response requirements for social reward, with notable individual variability. This choice procedure can identify mechanisms of individual differences in an animal model of cocaine use and could thereby help screen medications for people who are relatively unresponsive to treatments based on rewarding social interaction.
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Affiliation(s)
- Marco Venniro
- Intramural Research Program, NIDA, NIH, Baltimore, USA.
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
| | | | | | - Yavin Shaham
- Intramural Research Program, NIDA, NIH, Baltimore, USA.
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25
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Poisson CL, Engel L, Saunders BT. Dopamine Circuit Mechanisms of Addiction-Like Behaviors. Front Neural Circuits 2021; 15:752420. [PMID: 34858143 PMCID: PMC8631198 DOI: 10.3389/fncir.2021.752420] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/08/2021] [Indexed: 12/16/2022] Open
Abstract
Addiction is a complex disease that impacts millions of people around the world. Clinically, addiction is formalized as substance use disorder (SUD), with three primary symptom categories: exaggerated substance use, social or lifestyle impairment, and risky substance use. Considerable efforts have been made to model features of these criteria in non-human animal research subjects, for insight into the underlying neurobiological mechanisms. Here we review evidence from rodent models of SUD-inspired criteria, focusing on the role of the striatal dopamine system. We identify distinct mesostriatal and nigrostriatal dopamine circuit functions in behavioral outcomes that are relevant to addictions and SUDs. This work suggests that striatal dopamine is essential for not only positive symptom features of SUDs, such as elevated intake and craving, but also for impairments in decision making that underlie compulsive behavior, reduced sociality, and risk taking. Understanding the functional heterogeneity of the dopamine system and related networks can offer insight into this complex symptomatology and may lead to more targeted treatments.
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Affiliation(s)
- Carli L. Poisson
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
- Medical Discovery Team on Addiction, University of Minnesota, Minneapolis, MN, United States
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Liv Engel
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
- Medical Discovery Team on Addiction, University of Minnesota, Minneapolis, MN, United States
| | - Benjamin T. Saunders
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
- Medical Discovery Team on Addiction, University of Minnesota, Minneapolis, MN, United States
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, United States
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26
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Castillo Díaz F, Caffino L, Fumagalli F. Bidirectional role of dopamine in learning and memory-active forgetting. Neurosci Biobehav Rev 2021; 131:953-963. [PMID: 34655655 DOI: 10.1016/j.neubiorev.2021.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/05/2021] [Accepted: 10/11/2021] [Indexed: 12/15/2022]
Abstract
Dopaminergic neurons projecting from the Substantia Nigra to the Striatum play a critical role in motor functions while dopaminergic neurons originating in the Ventral Tegmental Area (VTA) and projecting to the Nucleus Accumbens, Hippocampus and other cortical structures regulate rewarding learning. While VTA mainly consists of dopaminergic neurons, excitatory (glutamate) and inhibitory (GABA) VTA-neurons have also been described: these neurons may also modulate and contribute to shape the final dopaminergic response, which is critical for memory formation. However, given the large amount of information that is handled daily by our brain, it is essential that irrelevant information be deleted. Recently, apart from the well-established role of dopamine (DA) in learning, it has been shown that DA plays a critical role in the intrinsic active forgetting mechanisms that control storage information, contributing to the deletion of a consolidated memory. These new insights may be instrumental to identify therapies for those disorders that involve memory alterations.
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Affiliation(s)
- Fernando Castillo Díaz
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Balzaretti 9, 20133 Milano, Italy.
| | - Lucia Caffino
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Balzaretti 9, 20133 Milano, Italy
| | - Fabio Fumagalli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Balzaretti 9, 20133 Milano, Italy
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27
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Vanderschuren LJMJ, Ahmed SH. Animal Models of the Behavioral Symptoms of Substance Use Disorders. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a040287. [PMID: 32513674 PMCID: PMC8327824 DOI: 10.1101/cshperspect.a040287] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To more effectively manage substance use disorders, it is imperative to understand the neural, genetic, and psychological underpinnings of addictive behavior. To contribute to this understanding, considerable efforts have been made to develop translational animal models that capture key behavioral characteristics of addiction on the basis of DSM5 criteria of substance use disorders. In this review, we summarize empirical evidence for the occurrence of addiction-like behavior in animals. These symptoms include escalation of drug use, neurocognitive deficits, resistance to extinction, exaggerated motivation for drugs, increased reinstatement of drug seeking after extinction, preference for drugs over nondrug rewards, and resistance to punishment. The occurrence of addiction-like behavior in laboratory animals has opened the opportunity to investigate the neural, genetic, and psychological background of key aspects of addiction, which may ultimately contribute to the prevention and treatment of substance use disorders.
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Affiliation(s)
- Louk J M J Vanderschuren
- Department of Animals in Science and Society, Division of Behavioural Neuroscience, Faculty of Veterinary Medicine, Utrecht University, 3584 CM Utrecht, the Netherlands
| | - Serge H Ahmed
- Université de Bordeaux, Bordeaux Neurocampus, Institut des Maladies Neurodégénératives, CNRS UMR 5293, F-33000 Bordeaux, France
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28
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Abstract
Substance use disorders (SUDs) are chronic brain diseases characterized by transitions from recreational to compulsive drug use and aberrant drug craving that persists for months to years after abstinence is achieved. The transition to compulsive drug use implies that plasticity is occurring, altering the physiology of the brain to precipitate addicted states. Epigenetic phenomena represent a varied orchestra of transcriptional tuning mechanisms that, in response to environmental stimuli, create and maintain gene expression-mediated physiological outcomes. Therefore, epigenetic mechanisms represent a convergent regulatory framework through which the plasticity required to achieve an addicted state can arise and then persist long after drug use has ended. In the first section, we will introduce basic concepts in epigenetics, such as chromatin architecture, histones and their posttranslational modifications, DNA methylation, noncoding RNAs, and transcription factors, along with methods for their investigation. We will then examine the implications of these mechanisms in SUDs, with a particular focus on cocaine-mediated neuroepigenetic plasticity across multiple behavioral models of addiction.
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Affiliation(s)
- Andrew F Stewart
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Sasha L Fulton
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Ian Maze
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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29
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Schwendt M, Knackstedt LA. Extinction vs. Abstinence: A Review of the Molecular and Circuit Consequences of Different Post-Cocaine Experiences. Int J Mol Sci 2021; 22:ijms22116113. [PMID: 34204090 PMCID: PMC8200945 DOI: 10.3390/ijms22116113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/16/2022] Open
Abstract
The intravenous cocaine self-administration model is widely used to characterize the neurobiology of cocaine seeking. When studies are aimed at understanding relapse to cocaine-seeking, a post-cocaine abstinence period is imposed, followed by “relapse” tests to assess the ability of drug-related stimuli (“primes”) to evoke the resumption of the instrumental response previously made to obtain cocaine. Here, we review the literature on the impact of post-cocaine abstinence procedures on neurobiology, finding that the prelimbic and infralimbic regions of the prefrontal cortex are recruited by extinction training, and are not part of the relapse circuitry when extinction training does not occur. Pairing cocaine infusions with discrete cues recruits the involvement of the NA, which together with the dorsal striatum, is a key part of the relapse circuit regardless of abstinence procedures. Differences in molecular adaptations in the NA core include increased expression of GluN1 and glutamate receptor signaling partners after extinction training. AMPA receptors and glutamate transporters are similarly affected by abstinence and extinction. Glutamate receptor antagonists show efficacy at reducing relapse following extinction and abstinence, with a modest increase in efficacy of compounds that restore glutamate homeostasis after extinction training. Imaging studies in humans reveal cocaine-induced adaptations that are similar to those produced after extinction training. Thus, while instrumental extinction training does not have face validity, its use does not produce adaptations distinct from human cocaine users.
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Affiliation(s)
- Marek Schwendt
- Psychology Department, University of Florida, Gainesville, FL 32611, USA;
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611, USA
| | - Lori A. Knackstedt
- Psychology Department, University of Florida, Gainesville, FL 32611, USA;
- Center for Addiction Research and Education, University of Florida, Gainesville, FL 32611, USA
- Correspondence: ; Tel.: +1-352-273-2185
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30
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Dopamine 'ups and downs' in addiction revisited. Trends Neurosci 2021; 44:516-526. [PMID: 33892963 DOI: 10.1016/j.tins.2021.03.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/14/2021] [Accepted: 03/16/2021] [Indexed: 12/11/2022]
Abstract
Repeated drug use can change dopamine (DA) function in ways that promote the development and persistence of addiction, but in what direction? By one view, drug use blunts DA neurotransmission, producing a hypodopaminergic state that fosters further drug use to overcome a DA deficiency. Another view is that drug use enhances DA neurotransmission, producing a sensitized, hyperdopaminergic reaction to drugs and drug cues. According to this second view, continued drug use is motivated by sensitization of drug 'wanting'. Here we discuss recent evidence supporting the latter view, both from preclinical studies using intermittent cocaine self-administration procedures that mimic human patterns of use and from related human neuroimaging studies. These studies have implications for the modeling of addiction in the laboratory and for treatment.
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31
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O'Connor SL, Aston-Jones G, James MH. The sensation seeking trait confers a dormant susceptibility to addiction that is revealed by intermittent cocaine self-administration in rats. Neuropharmacology 2021; 195:108566. [PMID: 33862028 DOI: 10.1016/j.neuropharm.2021.108566] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/19/2021] [Accepted: 04/09/2021] [Indexed: 01/14/2023]
Abstract
Heightened sensation seeking is associated with an increased risk of substance use disorder in clinical populations. In rats, sensation seeking is often examined by measuring locomotor reactivity to a novel environment. So-called high responders (HR) acquire self-administration of psychostimulants more quickly and consume higher amounts of drug compared to low responder (LR) rats, indicating that the HR trait might confer a stronger addiction propensity. However, studies of addiction-like behaviors in HR vs LR rats have typically utilized self-administration paradigms that do not dissociate individual differences in the hedonic/reinforcing and motivational properties of a drug. Moreover, little attention has been given to whether HR rats are more susceptible to drug-access conditions that promote a state-dependent addiction phenotype. We report that on a behavioral economics task, HR rats have higher preferred brain-cocaine levels compared to LR rats but do not differ with respect to their demand elasticity for cocaine. In contrast, when tested on an intermittent access schedule of cocaine self-administration, which has been shown to promote several addiction-related endophenotypes, HR rats exhibit greater escalation of intake and more drastic reductions in cocaine demand elasticity. Together, these data indicate that the HR trait does not confer higher extant addiction behavior, but rather that this phenotype is associated with a propensity for addiction that remains dormant until it is actuated by intermittent drug intake. These findings reveal a 'trait' (HR) by 'state' (intermittent drug intake) interaction that produces a strong addiction-like phenotype. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.
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Affiliation(s)
- Shayna L O'Connor
- Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University and Rutgers Biomedical Health Sciences, Piscataway, NJ, USA; Brain Health Institute, Rutgers University and Rutgers Biomedical and Health Sciences, Piscataway, NJ, USA
| | - Gary Aston-Jones
- Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University and Rutgers Biomedical Health Sciences, Piscataway, NJ, USA; Brain Health Institute, Rutgers University and Rutgers Biomedical and Health Sciences, Piscataway, NJ, USA
| | - Morgan H James
- Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University and Rutgers Biomedical Health Sciences, Piscataway, NJ, USA; Brain Health Institute, Rutgers University and Rutgers Biomedical and Health Sciences, Piscataway, NJ, USA.
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32
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Bidirectional role of acupuncture in the treatment of drug addiction. Neurosci Biobehav Rev 2021; 126:382-397. [PMID: 33839169 DOI: 10.1016/j.neubiorev.2021.04.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 02/06/2023]
Abstract
Drug addiction is a chronically relapsing disorder, affecting people from all walks of life. Studies of acupuncture effects on drug addiction are intriguing in light of the fact that acupuncture can be used as a convenient therapeutic intervention for treating drug addiction by direct activation of brain pathway. The current review aims to discuss the neurobiological mechanisms underlying acupuncture's effectiveness in the treatment of drug addiction, on the basis of two different theories (the incentive sensitization theory and the opponent process theory) that have seemingly opposite view on the role of the mesolimbic reward pathways in mediating compulsive drug-seeking behavior. This review provides evidence that acupuncture may reduce relapse to drug-seeking behavior by regulating neurotransmitters involved in drug craving modulation via somatosensory afferent mechanisms. Also, acupuncture normalizes hyper-reactivity or hypoactivity of the mesolimbic dopamine system in these opposed processes in drug addiction, suggesting bidirectional role of acupuncture in regulation of drug addiction. This proposes that acupuncture may reduce drug craving by correcting both dysfunctions of the mesolimbic dopamine pathway.
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33
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Nguyen D, Naffziger EE, Berridge KC. Positive Affect: Nature and brain bases of liking and wanting. Curr Opin Behav Sci 2021; 39:72-78. [PMID: 33748351 DOI: 10.1016/j.cobeha.2021.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The positive affect of rewards is an important contributor to well-being. Reward involves components of pleasure 'liking', motivation 'wanting', and learning. 'Liking' refers to the hedonic impact of positive events, with underlying mechanisms that include hedonic hotspots in limbic brain structures that amplify 'liking' reactions. 'Wanting' refers to incentive salience, a motivational process that makes reward cues attractive and able to trigger craving for their reward, mediated by larger dopamine-related mesocorticolimbic networks. Under normal conditions, 'liking' and 'wanting' cohere. However, 'liking' and 'wanting' can be dissociated by alterations in neural signaling, either induced in animal neuroscience laboratories or arising spontaneously in addictions and other affective disorders, which can be detrimental to positive well-being.
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Affiliation(s)
- David Nguyen
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Erin E Naffziger
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Kent C Berridge
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, United States
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34
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Lay BPP, Khoo SYS. Associative processes in addiction relapse models: A review of their Pavlovian and instrumental mechanisms, history, and terminology. NEUROANATOMY AND BEHAVIOUR 2021. [DOI: 10.35430/nab.2021.e18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Animal models of relapse to drug-seeking have borrowed heavily from associative learning approaches. In studies of relapse-like behaviour, animals learn to self-administer drugs then receive a period of extinction during which they learn to inhibit the operant response. Several triggers can produce a recovery of responding which form the basis of a variety of models. These include the passage of time (spontaneous recovery), drug availability (rapid reacquisition), extinction of an alternative response (resurgence), context change (renewal), drug priming, stress, and cues (reinstatement). In most cases, the behavioural processes driving extinction and recovery in operant drug self-administration studies are similar to those in the Pavlovian and behavioural literature, such as context effects. However, reinstatement in addiction studies have several differences with Pavlovian reinstatement, which have emerged over several decades, in experimental procedures, associative mechanisms, and terminology. Interestingly, in cue-induced reinstatement, drug-paired cues that are present during acquisition are omitted during lever extinction. The unextinguished drug-paired cue may limit the model’s translational relevance to cue exposure therapy and renders its underlying associative mechanisms ambiguous. We review major behavioural theories that explain recovery phenomena, with a particular focus on cue-induced reinstatement because it is a widely used model in addiction. We argue that cue-induced reinstatement may be explained by a combination of behavioural processes, including reacquisition of conditioned reinforcement and Pavlovian to Instrumental Transfer. While there are important differences between addiction studies and the behavioural literature in terminology and procedures, it is clear that understanding associative learning processes is essential for studying relapse.
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Affiliation(s)
- Belinda Po Pyn Lay
- Center for Studies in Behavioral Neurobiology/Groupe de Recherche en Neurobiologie Comportementale, Department of Psychology, Concordia University, Montreal, Canada
| | - Shaun Yon-Seng Khoo
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
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35
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Amphetamine maintenance therapy during intermittent cocaine self-administration in rats attenuates psychomotor and dopamine sensitization and reduces addiction-like behavior. Neuropsychopharmacology 2021; 46:305-315. [PMID: 32682325 PMCID: PMC7853073 DOI: 10.1038/s41386-020-0773-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 12/19/2022]
Abstract
D-amphetamine maintenance therapy shows promise as a treatment for people with cocaine addiction. Preclinical studies using Long Access (LgA) cocaine self-administration procedures suggest D-amphetamine may act by preventing tolerance to cocaine's effects at the dopamine transporter (DAT). However, Intermittent Access (IntA) cocaine self-administration better reflects human patterns of use, is especially effective in promoting addiction-relevant behaviors, and instead of tolerance, produces psychomotor, incentive, and neural sensitization. We asked, therefore, how D-amphetamine maintenance during IntA influences cocaine use and cocaine's potency at the DAT. Male rats self-administered cocaine intermittently (5 min ON, 25 min OFF x10; 5-h/session) for 14 sessions, with or without concomitant D-amphetamine maintenance therapy during these 14 sessions (5 mg/kg/day via s.c. osmotic minipump). We then assessed responding for cocaine under a progressive ratio schedule, responding under extinction and cocaine-primed reinstatement of drug seeking. We also assessed the ability of cocaine to inhibit dopamine uptake in the nucleus accumbens core using fast scan cyclic voltammetry ex vivo. IntA cocaine self-administration produced psychomotor (locomotor) sensitization, strong motivation to take and seek cocaine, and it increased cocaine's potency at the DAT. D-amphetamine co-administration suppressed the psychomotor sensitization produced by IntA cocaine experience. After cessation of D-amphetamine treatment, the motivation to take and seek cocaine was also reduced, and sensitization of cocaine's actions at the DAT was reversed. Thus, treatment with D-amphetamine might reduce cocaine use by preventing sensitization-related changes in cocaine potency at the DAT, consistent with an incentive-sensitization view of addiction.
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36
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Improving translation of animal models of addiction and relapse by reverse translation. Nat Rev Neurosci 2020; 21:625-643. [PMID: 33024318 DOI: 10.1038/s41583-020-0378-z] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2020] [Indexed: 12/13/2022]
Abstract
Critical features of human addiction are increasingly being incorporated into complementary animal models, including escalation of drug intake, punished drug seeking and taking, intermittent drug access, choice between drug and non-drug rewards, and assessment of individual differences based on criteria in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Combined with new technologies, these models advanced our understanding of brain mechanisms of drug self-administration and relapse, but these mechanistic gains have not led to improvements in addiction treatment. This problem is not unique to addiction neuroscience, but it is an increasing source of disappointment and calls to regroup. Here we first summarize behavioural and neurobiological results from the animal models mentioned above. We then propose a reverse translational approach, whose goal is to develop models that mimic successful treatments: opioid agonist maintenance, contingency management and the community-reinforcement approach. These reverse-translated 'treatments' may provide an ecologically relevant platform from which to discover new circuits, test new medications and improve translation.
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Interruption of continuous opioid exposure exacerbates drug-evoked adaptations in the mesolimbic dopamine system. Neuropsychopharmacology 2020; 45:1781-1792. [PMID: 32079024 PMCID: PMC7608117 DOI: 10.1038/s41386-020-0643-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 12/14/2022]
Abstract
Drug-evoked adaptations in the mesolimbic dopamine system are postulated to drive opioid abuse and addiction. These adaptations vary in magnitude and direction following different patterns of opioid exposure, but few studies have systematically manipulated the pattern of opioid administration while measuring neurobiological and behavioral impact. We exposed male and female mice to morphine for one week, with administration patterns that were either intermittent (daily injections) or continuous (osmotic minipump infusion). We then interrupted continuous morphine exposure with either naloxone-precipitated or spontaneous withdrawal. Continuous morphine exposure caused tolerance to the psychomotor-activating effects of morphine, whereas both intermittent and interrupted morphine exposure caused long-lasting psychomotor sensitization. Given links between locomotor sensitization and mesolimbic dopamine signaling, we used fiber photometry and a genetically encoded dopamine sensor to conduct longitudinal measurements of dopamine dynamics in the nucleus accumbens. Locomotor sensitization caused by interrupted morphine exposure was accompanied by enhanced dopamine signaling in the nucleus accumbens. To further assess downstream consequences on striatal gene expression, we used next-generation RNA sequencing to perform genome-wide transcriptional profiling in the nucleus accumbens and dorsal striatum. The interruption of continuous morphine exposure exacerbated drug-evoked transcriptional changes in both nucleus accumbens and dorsal striatum, dramatically increasing differential gene expression and engaging unique signaling pathways. Our study indicates that opioid-evoked adaptations in brain function and behavior are critically dependent on the pattern of drug administration, and exacerbated by interruption of continuous exposure. Maintaining continuity of chronic opioid administration may, therefore, represent a strategy to minimize iatrogenic effects on brain reward circuits.
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Mimicking Human Drug Consumption Patterns in Rat Engages Corticostriatal Circuitry. Neuroscience 2020; 442:311-313. [PMID: 32682655 DOI: 10.1016/j.neuroscience.2020.06.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 06/08/2020] [Indexed: 12/19/2022]
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Intermittent access cocaine self-administration produces psychomotor sensitization: effects of withdrawal, sex and cross-sensitization. Psychopharmacology (Berl) 2020; 237:1795-1812. [PMID: 32206828 PMCID: PMC7244391 DOI: 10.1007/s00213-020-05500-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/28/2020] [Indexed: 02/05/2023]
Abstract
RATIONALE With repeated administration, the psychomotor activating effects of drugs such as cocaine or amphetamine can change in very different ways-showing sensitization or tolerance-depending on whether they are administered more or less intermittently. This behavioral plasticity is thought to reflect, at least in part, changes in dopamine (DA) neurotransmission, and therefore, may provide insights into the development of substance use disorders. Indeed, the most widely used preclinical model of cocaine addiction, which involves Long Access (LgA) self-administration procedures, is reported to produce tolerance to cocaine's psychomotor activating effects and effects on DA activity. In contrast, Intermittent Access (IntA) cocaine self-administration is more effective than LgA in producing addiction-like behavior, but sensitizes DA neurotransmission. There is, however, very little information concerning the effects of IntA experience on the psychomotor activating effects of cocaine. OBJECTIVE The objective of this study was to determine whether IntA experience produces psychomotor sensitization with similar characteristics to that produced by the intermittent, noncontingent administration of cocaine. RESULTS IntA to cocaine did indeed produce psychomotor sensitization that (1) was greater after a long (30 days) vs. short (1 day) period of withdrawal, (2) was greater in females than males, and (3) resulted in cross-sensitization to another psychomotor stimulant drug, amphetamine. CONCLUSION The tolerance sometimes associated with LgA cocaine self-administration has been cited in support of the idea that, in addiction, drug-seeking and drug-taking is motivated to overcome a DA deficiency and associated anhedonia. In contrast, the neurobehavioral sensitization associated with IntA cocaine self-administration favors an incentive-sensitization view.
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Mascia P, Wang Q, Brown J, Nesbitt KM, Kennedy RT, Vezina P. Maladaptive consequences of repeated intermittent exposure to uncertainty. Prog Neuropsychopharmacol Biol Psychiatry 2020; 99:109864. [PMID: 31952958 PMCID: PMC7107980 DOI: 10.1016/j.pnpbp.2020.109864] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/13/2020] [Accepted: 01/13/2020] [Indexed: 12/28/2022]
Abstract
Recently we reported that nucleus accumbens (NAcc) dopamine (DA) tracks uncertainty during operant responding for non-caloric saccharin. We also showed that repeated intermittent exposure to this uncertainty, like exposure to drugs of abuse, leads to sensitization of the locomotor and NAcc DA effects of amphetamine and promotes the subsequent self-administration of the drug. Here we review these findings together with others showing that NAcc glutamate signaling is similarly affected by uncertainty. Extracellular levels of glutamate in this site also track uncertainty in a task in which nose poking for saccharin on an escalating variable ratio schedule of reinforcement is associated with progressively increasing variance between performance of the operant and payout. Furthermore, sensitized behavioral responding to and for amphetamine following exposure to uncertainty is accompanied by increased levels of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC) phosphorylation as well as altered protein levels of the transcription factor ∆FosB (increased) and glutamate transporter 1 (GLT1; decreased) in NAcc tissues. Notably, phosphorylation by CaMKII and PKC regulates AMPA receptor trafficking and function in this site, is elevated following psychostimulant exposure, and is necessary for the expression of enhanced drug taking. Increased ∆FosB and decreased GLT1 levels are observed following psychostimulant exposure, are associated with increased drug taking and seeking, and are known to modulate AMPA receptors and extracellular glutamate levels respectively. These adaptations in glutamate transmission as well as those observed with DA following repeated intermittent exposure to uncertainty are similar to those produced by exposure to abused drugs. Together, they point to the recruitment of both DA and glutamate signaling pathways in the NAcc in both drug and behavioral addictions. As uncertainty is central to games of chance, these findings have particular relevance for gambling disorders known to exhibit comorbidity with drug abuse.
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Affiliation(s)
- Paola Mascia
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL, United States
| | - Qiang Wang
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL, United States
| | - Jason Brown
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL, United States
| | - Kathryn M Nesbitt
- Department of Chemistry, Towson University, Towson, MD, United States
| | - Robert T Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - Paul Vezina
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL, United States.
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Allain F, Samaha AN. [Cocaine peaks and troughs. Modeling pathological drug use in rats]. Med Sci (Paris) 2020; 36:212-215. [PMID: 32228836 DOI: 10.1051/medsci/2020034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Florence Allain
- Département de pharmacologie et de physiologie, Groupe de recherche sur le système nerveux central, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Département de pharmacologie et de physiologie, Groupe de recherche sur le système nerveux central, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
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Kuhn BN, Kalivas PW, Bobadilla AC. Understanding Addiction Using Animal Models. Front Behav Neurosci 2019; 13:262. [PMID: 31849622 PMCID: PMC6895146 DOI: 10.3389/fnbeh.2019.00262] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/15/2019] [Indexed: 12/13/2022] Open
Abstract
Drug addiction is a neuropsychiatric disorder with grave personal consequences that has an extraordinary global economic impact. Despite decades of research, the options available to treat addiction are often ineffective because our rudimentary understanding of drug-induced pathology in brain circuits and synaptic physiology inhibits the rational design of successful therapies. This understanding will arise first from animal models of addiction where experimentation at the level of circuits and molecular biology is possible. We will review the most common preclinical models of addictive behavior and discuss the advantages and disadvantages of each. This includes non-contingent models in which animals are passively exposed to rewarding substances, as well as widely used contingent models such as drug self-administration and relapse. For the latter, we elaborate on the different ways of mimicking craving and relapse, which include using acute stress, drug administration or exposure to cues and contexts previously paired with drug self-administration. We further describe paradigms where drug-taking is challenged by alternative rewards, such as appetitive foods or social interaction. In an attempt to better model the individual vulnerability to drug abuse that characterizes human addiction, the field has also established preclinical paradigms in which drug-induced behaviors are ranked by various criteria of drug use in the presence of negative consequences. Separation of more vulnerable animals according to these criteria, along with other innate predispositions including goal- or sign-tracking, sensation-seeking behavior or impulsivity, has established individual genetic susceptibilities to developing drug addiction and relapse vulnerability. We further examine current models of behavioral addictions such as gambling, a disorder included in the DSM-5, and exercise, mentioned in the DSM-5 but not included yet due to insufficient peer-reviewed evidence. Finally, after reviewing the face validity of the aforementioned models, we consider the most common standardized tests used by pharmaceutical companies to assess the addictive potential of a drug during clinical trials.
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Affiliation(s)
| | - Peter W. Kalivas
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
| | - Ana-Clara Bobadilla
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
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Minogianis EA, Servonnet A, Filion MP, Samaha AN. Role of the orbitofrontal cortex and the dorsal striatum in incentive motivation for cocaine. Behav Brain Res 2019; 372:112026. [PMID: 31195036 DOI: 10.1016/j.bbr.2019.112026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 05/30/2019] [Accepted: 06/08/2019] [Indexed: 12/11/2022]
Abstract
Drug addiction involves increased incentive motivation for drug. Intermittent access to cocaine (IntA; 5-6 minutes ON, 25-26 minutes OFF, for 5-6 hours/session) enhances motivation to take the drug. The orbitofrontal cortex (OFC) and the dorsal striatum (DS) are part of a corticolimbic circuit that encodes incentive value and regulates reward-directed behaviour. We predicted that inactivation of the OFC, DS or both suppresses incentive motivation for cocaine after IntA experience. Male Wistar rats had IntA to cocaine (0.25 mg/kg/infusion) for 10 sessions. The rats developed a 'loading' pattern of intake, taking most of their cocaine in the first minute of each drug-available period. They also developed psychomotor sensitization to self-administered cocaine. We then measured incentive motivation for cocaine using a progressive ratio schedule of reinforcement (PR). Before some PR sessions, rats received microinfusions of a baclofen/muscimol cocktail (0.3 and 0.03 nmol/hemisphere, respectively, or saline) to temporarily inactivate the OFC or DS, or to disconnect the two regions. None of these treatments changed spontaneous locomotion in cocaine-naïve rats. However, both baclofen/muscimol and saline infusions influenced cocaine self-administration behaviour. Infusing baclofen/muscimol or saline into the OFC or into the OFC and contralateral DS decreased responding for cocaine under PR, with baclofen/muscimol and saline having similar effects, except that only OFC-DS disconnection with baclofen/muscimol slowed the pace of cocaine intake. Baclofen/muscimol or saline into the DS also reduced responding for cocaine under PR, but baclofen/muscimol was more effective. We conclude that neuronal activity in the OFC and DS might regulate incentive motivation for cocaine.
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Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada
| | - Alice Servonnet
- Department of Neuroscience, Faculty of Medicine, Université de Montréal, Canada
| | - Marie-Pier Filion
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Canada; Central Nervous System Research Group (GRSNC), Faculty of Medicine, Université de Montréal, Canada.
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The transition to cocaine addiction: the importance of pharmacokinetics for preclinical models. Psychopharmacology (Berl) 2019; 236:1145-1157. [PMID: 30820634 PMCID: PMC6592776 DOI: 10.1007/s00213-019-5164-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 01/03/2019] [Indexed: 01/10/2023]
Abstract
A key question in addiction research concerns how, in some individuals, initial recreational or casual patterns of drug use may change brain and psychological function in ways that promote a transition to the problematic patterns of use that define substance use disorders (addiction). In preclinical studies, this is modeled using self-administration procedures. However, most cocaine self-administration procedures produce continuously high brain concentrations of drug, whereas in people, bouts of use are thought to be more intermittent. Here, we ask whether such temporal pharmacokinetic factors matter, by comparing and contrasting the neuropsychological consequences of intermittent vs. long access cocaine self-administration experience. It turns out, the temporal pattern of cocaine use has profound effects on a number of outcomes. First, despite much less total drug consumption, intermittent access to cocaine is more effective in producing addiction-like behavior. Second, intermittent and long access cocaine self-administration change the brain in very different ways to influence motivated behavior. We argue that intermittent access self-administration procedures might be better suited than traditional self-administration procedures for isolating drug-induced changes in neuropsychological function that contribute to the transition to cocaine addiction.
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