1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Lamb RJ, Schindler CW, Ginsburg BC. Effects of an ethanol-paired conditioned stimulus on responding for ethanol suppressed by a conditioned-taste-aversion. Alcohol 2024; 116:1-8. [PMID: 37774959 DOI: 10.1016/j.alcohol.2023.09.008] [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: 12/22/2022] [Revised: 09/25/2023] [Accepted: 09/26/2023] [Indexed: 10/01/2023]
Abstract
Ethanol-Paired Conditioned Stimuli (CS) can increase ethanol-responding either in extinction or occurring at low rates late in a session. To examine the generality of CS-induced increases in ethanol-responding, we examined whether a CS could increase responding suppressed by Conditioned-Taste-Aversion (CTA), which presumably suppresses responding by changing ethanol's valence from positive to negative. Rats were trained to respond for ethanol under a Random Interval (RI) schedule. We then removed the lever and paired Random-Time ethanol deliveries with illumination of a stimulus light (i.e., CS) for 10 sessions. Results were compared with a Truly Random Control group, in which the light and ethanol deliveries occurred independently. In a subsequent experiment, rats were treated similarly, except the light served as a discriminative stimulus, as the lever was extended and ethanol deliveries were available under a RI during light presentations. After this training, the lever was returned and rats again responded for ethanol. Subsequently, sessions were followed by LiCl administration. When responding reached low levels, LiCl administration stopped and the light was occasionally illuminated during the session. Responding during the light presentation was compared to responding during the period preceding light presentation. Responding partially recovered across 10 sessions and was greater during light presentations than in the period before it in all three groups. Increases were not reliably different between the groups, indicating that explanations for these increases such as CS-induced increases in motivation or approach toward the light are unlikely to be correct. The most likely explanation for these light-induced increases is that during sessions in which the light had been presented previously, LiCl had never been presented and thus, the light had come to signal that ethanol was safe to drink.
Collapse
Affiliation(s)
- R J Lamb
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
| | - C W Schindler
- Designer Drug Unit, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, United States
| | - Brett C Ginsburg
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| |
Collapse
|
3
|
Tegelbeckers J, Porter DB, Voss JL, Schoenbaum G, Kahnt T. Lateral orbitofrontal cortex integrates predictive information across multiple cues to guide behavior. Curr Biol 2023; 33:4496-4504.e5. [PMID: 37804827 PMCID: PMC10622115 DOI: 10.1016/j.cub.2023.09.033] [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: 06/08/2023] [Revised: 08/21/2023] [Accepted: 09/13/2023] [Indexed: 10/09/2023]
Abstract
Individuals are often faced with multiple cues that concurrently predict the same outcome, and combining these predictions may benefit behavior. Previous work has studied the neural basis of decision-making, predominantly using isolated sensory stimuli, and so the mechanisms that allow us to leverage multiple cues remain unclear. In two experiments, we used neuroimaging and network-targeted brain stimulation to probe how the brain integrates outcome predictions to guide adaptive behavior. We identified neural signatures of outcome integration in the lateral orbitofrontal cortex (OFC), where concurrently presented cues evoke stronger pattern-based representations of expected outcomes. Moreover, perturbing lateral OFC network activity impairs subjects' ability to leverage predictions from multiple cues to facilitate responding. Intriguingly, we found similar behavioral and brain mechanisms for reward-predicting cues and for cues predicting the absence of reward. These findings highlight a causal role for the lateral OFC in utilizing outcome predictions from multiple cues to guide behavior.
Collapse
Affiliation(s)
- Jana Tegelbeckers
- Northwestern University, Feinberg School of Medicine, 420 E Superior St, Chicago, IL 60611, USA; Otto von Guericke University, Universitaetsplatz 2, 39106 Magdeburg, Germany.
| | - Daria B Porter
- Northwestern University, Feinberg School of Medicine, 420 E Superior St, Chicago, IL 60611, USA
| | - Joel L Voss
- University of Chicago, 5841 S Maryland Ave, Chicago, IL 60637, USA
| | - Geoffrey Schoenbaum
- National Institute on Drug Abuse Intramural Research Program, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Thorsten Kahnt
- National Institute on Drug Abuse Intramural Research Program, 251 Bayview Blvd, Baltimore, MD 21224, USA.
| |
Collapse
|
4
|
AlTfaili H, Ginsburg BC, Lamb RJ. Ethanol-paired conditioned stimulus effects on concurrent reinforced responding for ethanol and food. Alcohol 2023; 111:17-23. [PMID: 36898642 PMCID: PMC10512455 DOI: 10.1016/j.alcohol.2023.02.002] [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: 11/18/2022] [Revised: 02/09/2023] [Accepted: 02/27/2023] [Indexed: 03/11/2023]
Abstract
The influence of Pavlovian Conditioned Stimuli (CS) on ethanol self-administration and choice between ethanol and an alternative are potentially important. Ethanol-paired CS might increase ethanol self-administration, especially when it has been reduced during recovery, though the selectivity of these increases has been questioned. To date, one study examined the effects of an ethanol-paired CS on ethanol choice and found that the CS increased ethanol-responding more than food-responding when both were in extinction. However, it remains unclear whether ethanol-paired CS increase ethanol-choice that is not in extinction. Here, we examine the effects of an ethanol-paired CS on ethanol-choice when both food- and ethanol-responding are reinforced. Sixteen adult male Lewis rats were trained on a concurrent schedule to respond for ethanol on one lever and for food on the other lever. Ethanol was available under an FR 5 schedule, and food was available under an FR schedule that was adjusted for each rat to earn an equal number of food and ethanol deliveries. Then, 2-min light presentations were paired with an RT 25-sec schedule of ethanol delivery for 10 sessions in the absence of both levers. After this, subjects were placed back on the concurrent schedule for one session, then five sessions with the CS being present or absent on each trial of the concurrent schedule occurred. Rats learned to respond on one lever for ethanol and on the other for food and earned similar numbers of ethanol and food deliveries. During Pavlovian Conditioning, the number of head entries into the head-entry detector was higher in the presence of the CS than in its absence. In the test sessions, rats made more ethanol responses in the presence of the CS than in its absence. However, this effect was small and did not increase the amount of ethanol earned. Thus, ethanol-paired CS could increase ethanol-responding under a choice procedure but did not increase ethanol consumption meaningfully under the studied conditions.
Collapse
Affiliation(s)
- Hanana AlTfaili
- Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Brett C Ginsburg
- Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - R J Lamb
- Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| |
Collapse
|
5
|
Humburg BA, Bardo MT. Renewal of cocaine seeking using social and nonsocial contextual stimuli. Psychopharmacology (Berl) 2023:10.1007/s00213-023-06414-7. [PMID: 37391496 PMCID: PMC10806405 DOI: 10.1007/s00213-023-06414-7] [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: 04/26/2023] [Accepted: 06/20/2023] [Indexed: 07/02/2023]
Abstract
RATIONALE Various nonsocial cues have been used as stimuli to examine the contextual control of drug seeking behavior, but little is known about the role of social stimuli. OBJECTIVES This study determined if renewal of cocaine seeking is differentially controlled using a context consisting of either a social peer and/or house light illumination. METHODS In Experiment 1, male and female rats trained to self-administer cocaine in the presence of a same-sex social peer and house light illumination (context A). Following self-administration, rats were randomly assigned to either an AAA (control) or ABA (renewal) group for extinction. For AAA rats, extinction consisted of the same context A as self-administration; for ABA rats, extinction occurred without the peer or house light (context B). Following extinction, renewal of cocaine seeking occurred by testing the peer alone, house light alone, and the peer + house light combination. Experiment 2 was conducted to ensure that the house light alone was sufficiently salient to produce renewal. RESULTS Both experiments showed that rats acquired cocaine self-administration and extinguished lever pressing. In Experiment 1, the ABA group renewed cocaine seeking to the peer and peer + house light, but not to the house light alone. In Experiment 2, ABA rats renewed cocaine seeking to the house light alone, indicating it was sufficiently salient to produce renewal. The AAA group did not show renewal in either experiment. CONCLUSION Social peers serve as powerful stimuli that can overshadow nonsocial visual stimuli in the renewal of cocaine seeking.
Collapse
Affiliation(s)
- Bree A Humburg
- Department of Psychology, University of Kentucky, Biomedical Biological Science Research Building, Room 447, 741 S. Limestone, Lexington, KY, 40536-0509, USA
| | - Michael T Bardo
- Department of Psychology, University of Kentucky, Biomedical Biological Science Research Building, Room 447, 741 S. Limestone, Lexington, KY, 40536-0509, USA.
| |
Collapse
|
6
|
Ritchey CM, Kuroda T, Podlesnik CA. Evaluating effects of context changes on resurgence in humans. Behav Processes 2021; 194:104563. [PMID: 34871750 DOI: 10.1016/j.beproc.2021.104563] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/23/2021] [Accepted: 12/01/2021] [Indexed: 12/29/2022]
Abstract
Laboratory models of relapse provide methods for evaluating challenges to behavioral treatments with differential reinforcement of an alternative response (DRA). Resurgence occurs with the worsening of conditions of reinforcement for appropriate behavior and renewal occurs when transitioning out of a treatment context. Across five experiments, participants recruited via online crowdsourcing pressed onscreen buttons to earn points exchangeable for money and contexts sometimes changed through changes in the background image. Returning to the training context (ABA, Experiment 1) and transitioning to a novel context (ABC, Experiment 2) produced greater resurgence when removing alternative reinforcement in comparison with remaining in the treatment context (ABB). In contrast, we observed little difference in resurgence among AAA, ABB, and AAC context manipulations (Experiment 3) and ABA, ABC, and AAC context manipulations (Experiment 4). In Experiment 5, we evaluated relative contributions of the presence versus absence of context changes (ABA vs. ABB) in combination with or without the removal of alternative reinforcement. Both changing context and removing alternative reinforcement increased responding in isolation and the combination produced greater-than-additive effects. Overall, the present findings demonstrate a consistent effect of removing alternative reinforcement on relapse that, under certain conditions, can be enhanced by context change.
Collapse
|
7
|
Modrak CG, Giesler LP, Vonder Haar C. Traumatic brain injury substantially reduces the conditioned reinforcing effects of environmental cues in rats. Brain Res 2020; 1748:147084. [PMID: 32871136 DOI: 10.1016/j.brainres.2020.147084] [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: 06/18/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 12/22/2022]
Abstract
Traumatic brain injury affects millions of people each year and is an established risk factor for addiction. Recent animal studies have causally demonstrated that injuries can increase drug self-administration across a variety of substances. One potential behavioral mediator for this finding is an increased responsivity to drug-associated cues. This endophenotype can be identified by profiling non-drug-related behaviors. The current study evaluated several paradigms (conditioned approach, conditioned reinforcement, extinction from variable interval responding, conditioned facilitation) to determine how rats with a frontal TBI differed in their response to Pavlovian conditioning in response to food-paired cues. Surprisingly, rats with a TBI demonstrated increased goal-tracking in a conditioned approach paradigm and exerted less effort for a conditioned reinforcer. Moreover, they had slightly facilitated extinction (as demonstrated by significantly larger interresponse times) in the face of reinforcer-associated cues. Despite these effects, TBI rats still demonstrated conditioned facilitation to an auditory stimulus. Together, these effects suggest a phenotype in the opposite direction of what might be anticipated. Cues still served a strong discriminative function and altered behavior; however, they did not function as strong conditioned reinforcers for TBI animals. One potential reason for this is that substantial changes to the dopamine system after TBI may reduce the conditioned reinforcing effects of cues, but sensitize the brain to potent drugs of abuse. More research will be needed to determine whether this is the case.
Collapse
Affiliation(s)
- Cassandra G Modrak
- Injury and Recovery Laboratory, Department of Psychology, West Virginia University, Morgantown, WV, USA
| | - Lauren P Giesler
- Injury and Recovery Laboratory, Department of Psychology, West Virginia University, Morgantown, WV, USA
| | - Cole Vonder Haar
- Injury and Recovery Laboratory, Department of Psychology, West Virginia University, Morgantown, WV, USA; Department of Neuroscience, West Virginia University, Morgantown, WV, USA.
| |
Collapse
|
8
|
Hogarth L, Field M. Relative expected value of drugs versus competing rewards underpins vulnerability to and recovery from addiction. Behav Brain Res 2020; 394:112815. [PMID: 32707138 PMCID: PMC7495042 DOI: 10.1016/j.bbr.2020.112815] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 07/13/2020] [Accepted: 07/17/2020] [Indexed: 12/13/2022]
Abstract
Behavioural economic theories of addiction contend that greater expected value of drug relative to alternative non-drug rewards is the core mechanism underpinning vulnerability to and recovery from addiction. To evaluate this claim, we exhaustively review studies with human drug users that have measured concurrent choice between drugs vs. alternative rewards, and explored individual differences. These studies show that drug choice can be modulated by drug cues, drug devaluation, imposition of costs/punishment and negative mood induction. Regarding individual differences, dependence severity was reliably associated with overall drug preference, and self-reported drug use to cope with negative affect was reliably associated with greater sensitivity to mood induced increases in drug choice. By contrast, there were no reliable individual differences in sensitivity to the effect of drug cues, drug devaluation or punishment on drug choice. These findings provide insight into the mechanisms that underpin vulnerability to dependence: vulnerability is conferred by greater relative value ascribed to drugs, and relative drug value is further augmented by negative affective states in those who report drug use coping motives. However, dependence does not appear to be characterised by abnormal cue-reactivity, habit learning or compulsion. We then briefly review emerging literature which demonstrates that therapeutic interventions and recovery from addiction might be attributed to changes in the expected relative value of drug versus alternative rewards. Finally, we outline a speculative computational account of the distortions in decision-making that precede action selection in addiction, and we explain how this account provides a blueprint for future research on the determinants of drug choice, and mechanisms of treatment and recovery from addiction. We conclude that a unified economic decision-making account of addiction has great promise in reconciling diverse addiction theories, and neuropsychological evaluation of the underlying decision mechanisms is a fruitful area for future research and treatment.
Collapse
Affiliation(s)
- Lee Hogarth
- Lee Hogarth, School of Psychology, University of Exeter, Washington Singer Building, Perry Road, Exeter EX4 4QG, UK.
| | - Matt Field
- Department of Psychology, University of Sheffield
| |
Collapse
|
9
|
Huskinson SL. Unpredictability as a modulator of drug self-administration: Relevance for substance-use disorders. Behav Processes 2020; 178:104156. [PMID: 32526314 DOI: 10.1016/j.beproc.2020.104156] [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: 01/30/2020] [Revised: 05/14/2020] [Accepted: 05/29/2020] [Indexed: 01/05/2023]
Abstract
Drug self-administration has been regarded as a gold-standard preclinical model of addiction and substance-use disorder (SUD). However, investigators are becoming increasingly aware, that certain aspects of addiction or SUDs experienced by humans are not accurately captured in our preclinical self-administration models. The current review will focus on two such aspects of current preclinical drug self-administration models: 1) Predictable vs. unpredictable drug access in terms of the time and effort put into obtaining drugs (i.e., response requirement) and drug quality (i.e., amount) and 2) rich vs. lean access to drugs. Some behavioral and neurobiological mechanisms that could contribute to excessive allocation of behavior toward drug-seeking and drug-taking at the expense of engaging in nondrug-related activities are discussed, and some directions for future research are identified. Based on the experiments reviewed, lean and unpredictable drug access could worsen drug-seeking and drug-taking behavior in individuals with SUDs. Once more fully explored, this area of research will help determine whether and how unpredictable and lean cost requirements affect drug self-administration in preclinical laboratory studies with nonhuman subjects and will help determine whether incorporating these conditions in current self-administration models will increase their predictive validity.
Collapse
Affiliation(s)
- Sally L Huskinson
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500N. State Street, Jackson, MS, 39216, United States.
| |
Collapse
|
10
|
Shoaib M, Perkins KA. Preclinical and clinical research on the discriminative stimulus effects of nicotine. Neuropharmacology 2020; 170:108063. [PMID: 32220607 DOI: 10.1016/j.neuropharm.2020.108063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/18/2020] [Accepted: 03/19/2020] [Indexed: 02/06/2023]
Abstract
Across species, nicotine can produce robust discriminative stimulus (DS) effects, as with other drugs of abuse, a feature that has been harnessed to advance our understanding on the neuropharmacological mechanisms of nicotine's actions. With the crucial role played by nicotine in supporting tobacco dependence, nicotine DS effects have presented an ideal platform to develop novel generation of smoking cessation compounds. Findings from preclinical strands of research have invigorated the field of human discrimination research to objectively assess nicotine's interoceptive stimulus effects. As such, translation studies provide proof of concept for nicotine DS research as a method to assess the subjective effects of nicotine per se, separate from non-nicotine stimuli involved in smoking. Recent clinical studies with low doses have demonstrated that perceiving nicotine's DS effects is necessary, yet not sufficient, for that dose to be reinforcing. These measures have been instrumental in developing novel strategies with regards to establishing threshold doses of nicotine contained in tobacco products, to then determine subthreshold doses that cannot be discriminated and, therefore, fail to maintain reinforcement. Findings from preclinical and clinical nicotine DS research could substantially inform public health policies aimed at regulating nicotine content of consumer products so that they minimize risks of dependency. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
Collapse
Affiliation(s)
- Mohammed Shoaib
- Institute of Neuroscience, The Medical School, Newcastle University, Newcastle, NE2 4HH, UK.
| | - Kenneth A Perkins
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| |
Collapse
|
11
|
Early life stress and the propensity to develop addictive behaviors. Int J Dev Neurosci 2019; 78:156-169. [PMID: 31255718 DOI: 10.1016/j.ijdevneu.2019.06.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 06/03/2019] [Accepted: 06/13/2019] [Indexed: 12/14/2022] Open
Abstract
There is a vast literature on effects of early life manipulations in rodents much of which is aimed at investigating the long-term consequences related to emotion and cognition in adulthood. Less is known about how these manipulations affect responses reflective of alcohol (AUD) and substance (SUD) use disorders. The purpose of this paper is to review the literature of studies that employed early life manipulations and assessed behavioral responses to psychoactive substances, specifically alcohol, opiates, and stimulants, in rodents. While the findings with alcohol are more limited and mixed, studies with opiates and stimulants show strong support for the ability of these manipulations to enhance behavioral responsivity to these substances in line with epidemiological data. Some outcomes show sex differences. The mechanisms that influence these enduring changes may reflect epigenetic alterations. Several studies support a role for altered DNA methylation (and other epigenetic mechanisms) as biological responses to early environmental insults. The chemical changes induced by DNA methylation affect transcriptional activity of DNA and thus can have a long-term impact on the individual's phenotype. Such effects are particularly robust when they occur during sensitive periods of brain development (e.g., first postnatal weeks in rodents). We review this emerging literature as it relates to the known neurobiology of AUDs and SUDs and suggest new avenues of research. Such findings will have implications for the treatment and prevention of AUDs and SUDs and could provide insight into factors that support resiliency.
Collapse
|
12
|
Conklin CA, McClernon FJ, Vella EJ, Joyce CJ, Salkeld RP, Parzynski CS, Bennett L. Combined Smoking Cues Enhance Reactivity and Predict Immediate Subsequent Smoking. Nicotine Tob Res 2019; 21:241-248. [PMID: 29370401 PMCID: PMC6329405 DOI: 10.1093/ntr/nty009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022]
Abstract
Introduction Cue reactivity (CR) research has reliably demonstrated robust cue-induced responding among smokers exposed to common proximal smoking cues (eg, cigarettes, lighter). More recent work demonstrates that distal stimuli, most notably the actual environments in which smoking previously occurred, can also gain associative control over craving. In the real world, proximal cues always occur within an environment; thus, a more informative test of how cues affect smokers might be to present these two cue types simultaneously. Methods Using a combined-cue counterbalanced CR paradigm, the present study tested the impact of proximal (smoking and neutral) + personal environment (smoking and nonsmoking places) pictorial cues, on smokers' subjective and behavioral CR; as well as the extent to which cue-induced craving predicts immediate subsequent smoking in a within-subjects design. Results As anticipated, the dual smoking cue combination (ProxS + EnvS) led to the greatest cue-induced craving relative to the other three cue combinations (ProxS + EnvN, ProxN + EnvS, and ProxN ± EnvN), ps < .004. Dual smoking cues also led to significantly shorter post-trial latencies to smoke, ps < .01. Overall CR difference score (post-trial craving minus baseline craving) was predictive of subsequent immediate smoking indexed by: post-trial latency to smoke [B = -2.69, SE = 9.02; t(143) = -2.98, p = .003]; total puff volume [B = 2.99, SE = 1.13; t(143) = 2.65, p = .009]; and total number of puffs [B = .053, SE = .027; t(143) = 1.95, p = .05]. Conclusions The implications of these findings for better understanding the impact of cues on smoking behavior and cessation are discussed. Implications This novel cue reactivity study examined smokers' reactivity to combined proximal and distal smoking cues. Exposure to a combination of two smoking cues (proximal and environment) led to the greatest increases in cue-induced craving and smoking behavior compared to all other cue combinations. Further, the overall magnitude of cue-induced craving was found to significantly predict immediate subsequent smoking. This work provides new insight on how exposure to various cues and cue combinations directly affect smokers' craving and actual smoking behavior, as well as the relationship between those two indices of reactivity.
Collapse
Affiliation(s)
| | - F Joseph McClernon
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC
| | - Elizabeth J Vella
- Department of Psychology, University of Southern Maine, Portland, ME
| | | | - Ronald P Salkeld
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA
| | | | - Lee Bennett
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA
| |
Collapse
|
13
|
Gutman AL, Ewald VA, Cosme CV, Worth WR, LaLumiere RT. The infralimbic and prelimbic cortices contribute to the inhibitory control of cocaine-seeking behavior during a discriminative stimulus task in rats. Addict Biol 2017; 22:1719-1730. [PMID: 27549035 DOI: 10.1111/adb.12434] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/13/2016] [Accepted: 07/05/2016] [Indexed: 12/20/2022]
Abstract
The infralimbic and prelimbic (IL and PL, respectively) regions of the medial prefrontal cortex regulate the control of drug-seeking behavior. However, their roles in cocaine seeking in a discriminative stimulus (DS)-based self-administration task are unclear. To address this issue, male Sprague Dawley rats were trained on a DS task in which, on a trial-by-trial basis, a DS+ indicated that a lever press would produce a cocaine infusion, whereas a distinct DS- indicated that a lever press would produce nothing. IL and PL inactivation via GABA receptor activation decreased performance accuracy and disinhibited behavioral responding on DS- trials, resulting in greater lever pressing during the DS- presentation. This was accompanied by a decrease in cocaine infusions obtained, a finding confirmed in a subsequent experiment using a standard FR1 cocaine self-administration paradigm. We repeated the DS study using a food reward and found that inactivation of each region decreased performance accuracy but had no effect on the total number of food pellets earned. Additional experiments with the cocaine DS task found that dopamine receptor blockade in the IL, but not PL, reduced performance accuracy and disinhibited behavioral responding on DS- trials, whereas AMPA receptor blockade in the IL and PL had no effect on performance accuracy. These findings strongly suggest that, in a DS-based self-administration task in which rats must actively decide whether to engage in lever pressing (DS+) or withhold lever pressing (DS-) on a trial-by-trial basis, both the IL and PL contribute to the inhibitory control of drug-seeking behavior.
Collapse
Affiliation(s)
- Andrea L. Gutman
- Department of Psychological and Brain Sciences; University of Iowa; Iowa City IA USA
| | - Victoria A. Ewald
- Interdisciplinary Graduate Program in Neuroscience; University of Iowa; Iowa City IA USA
| | - Caitlin V. Cosme
- Department of Psychological and Brain Sciences; University of Iowa; Iowa City IA USA
| | - Wensday R. Worth
- Department of Psychological and Brain Sciences; University of Iowa; Iowa City IA USA
| | - Ryan T. LaLumiere
- Department of Psychological and Brain Sciences; University of Iowa; Iowa City IA USA
- Interdisciplinary Graduate Program in Neuroscience; University of Iowa; Iowa City IA USA
| |
Collapse
|
14
|
Troisi JR. Pavlovian Extinction of the Discriminative Stimulus Effects of Nicotine and Ethanol in Rats Varies as a Function of Context. PSYCHOLOGICAL RECORD 2017. [DOI: 10.1007/bf03395756] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
15
|
Weiss SJ, Kearns DN. Cocaine cues retain silent traces of an excitatory history after conversion into conditioned inhibitors: 'the ghost in the addict'. Behav Pharmacol 2016; 27:293-300. [PMID: 26866969 DOI: 10.1097/fbp.0000000000000220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The present experiment investigated the extent to which the A+/AB- conditioned inhibition procedure could counteract an excitatory drug-related conditioning history. In two groups of rats, a light stimulus was established as a signal for the absence of cocaine. For the History group, the light had previously been a discriminative stimulus (S) that occasioned cocaine self-administration and could thus be classified as a cocaine excitor. In comparison, the No-History group first encountered the light during conditioned inhibition training. During conditioned inhibition training, both groups self-administered cocaine during tone as well as during click Ss, whereas drug seeking was eliminated in click-plus-light, wherein cocaine was not available (A+/AB-). Drug seeking was essentially eliminated in both groups. Nevertheless, on a summation test the light reduced cocaine seeking occasioned by the tone S by 95% in the No-History group, but by less than 50% in the History group. This summation test result showed that the effects of a drug-related history persisted even after the light was converted into an effective conditioned inhibitor on the training baseline through the powerful A+/AB- procedure. Future research should seek procedures that produce even stronger conditioned inhibition that eliminates such residual 'silent' drug excitation, the 'ghost in the addict'.
Collapse
Affiliation(s)
- Stanley J Weiss
- Department of Psychology, American University, Washington, District of Columbia, USA
| | | |
Collapse
|
16
|
Lamb RJ, Schindler CW, Pinkston JW. Conditioned stimuli's role in relapse: preclinical research on Pavlovian-Instrumental-Transfer. Psychopharmacology (Berl) 2016; 233:1933-44. [PMID: 26800688 PMCID: PMC4863941 DOI: 10.1007/s00213-016-4216-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/12/2016] [Indexed: 01/24/2023]
Abstract
RATIONALE AND OBJECTIVE Pavlovian learning is central to many theories of addiction. In these theories, stimuli paired with drug ingestion become conditioned stimuli (CS) and subsequently elicit drug-seeking and drug-taking. However, in most relevant studies, Pavlovian and instrumental learning are confounded. This confound may be avoided in Pavlovian-Instrumental-Transfer (PIT) procedures. In PIT, Pavlovian and instrumental learning are established separately and then combined. In order to better understand the role of CSs in addiction, we review the relevant studies using PIT. FINDINGS We identified seven articles examining PIT effects of ethanol- or cocaine-paired CSs. Under at least one condition, six of these articles reported CS-elicited increases in responding previously maintained by drug. However, the only study using the optimal control condition failed to find a CS-elicited increase. Two studies examining CS specificity found the CS also increased responding maintained by a different reinforcer. Two studies examined if CSs elicit increases in actual drug-taking. Both failed to find CS-elicited increases, i.e., no study shows CS-elicited increases in actual drug-taking. Further, CS-elicited increases in extinguished responding are short-lived. CONCLUSIONS These findings are not entirely consistent with Pavlovian learning playing a central role in addiction. However, design issues can explain most of these inconsistencies. Studies without these design issues are needed. Additionally, existing theories hypothesize drug-paired CSs increase drug-taking by increasing motivation, by eliciting conditioned responses that make drug-seeking more probable, or by a combination of these. Work distinguishing between these mechanisms would also be useful.
Collapse
Affiliation(s)
- R J Lamb
- Departments of Psychiatry & Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA.
| | - Charles W Schindler
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Jonathan W Pinkston
- Department of Behavioral Analysis, University of North Texas, 360 G Chilton Hall, Avenue C, Denton, TX, 76208, USA
| |
Collapse
|
17
|
Abstract
It is important to characterize the learning processes governing tobacco-seeking in order to understand how best to treat this behavior. Most drug learning theories have adopted a Pavlovian framework wherein the conditioned response is the main motivational process. We favor instead a hierarchical instrumental decision account, wherein expectations about the instrumental contingency between voluntary tobacco-seeking and the receipt of nicotine reward determines the probability of executing this behavior. To support this view, we review titration and nicotine discrimination research showing that internal signals for deprivation/satiation modulate expectations about the current incentive value of smoking, thereby modulating the propensity of this behavior. We also review research on cue-reactivity which has shown that external smoking cues modulate expectations about the probability of the tobacco-seeking response being effective, thereby modulating the propensity of this behavior. Economic decision theory is then considered to elucidate how expectations about the value and probability of response-nicotine contingency are integrated to form an overall utility estimate for that option for comparison with qualitatively different, nonsubstitute reinforcers, to determine response selection. As an applied test for this hierarchical instrumental decision framework, we consider how well it accounts for individual liability to smoking uptake and perseveration, pharmacotherapy, cue-extinction therapies, and plain packaging. We conclude that the hierarchical instrumental account is successful in reconciling this broad range of phenomenon precisely because it accepts that multiple diverse sources of internal and external information must be integrated to shape the decision to smoke.
Collapse
Affiliation(s)
- Lee Hogarth
- School of Psychology, University of Exeter, Washington Singer Building, Perry Road, Exeter Ex4 4QG, UK,
| | | |
Collapse
|
18
|
Perry CJ, Zbukvic I, Kim JH, Lawrence AJ. Role of cues and contexts on drug-seeking behaviour. Br J Pharmacol 2014; 171:4636-72. [PMID: 24749941 PMCID: PMC4209936 DOI: 10.1111/bph.12735] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 04/04/2014] [Accepted: 04/10/2014] [Indexed: 01/15/2023] Open
Abstract
Environmental stimuli are powerful mediators of craving and relapse in substance-abuse disorders. This review examined how animal models have been used to investigate the cognitive mechanisms through which cues are able to affect drug-seeking behaviour. We address how animal models can describe the way drug-associated cues come to facilitate the development and persistence of drug taking, as well as how these cues are critical to the tendency to relapse that characterizes substance-abuse disorders. Drug-associated cues acquire properties of conditioned reinforcement, incentive motivation and discriminative control, which allow them to influence drug-seeking behaviour. Using these models, researchers have been able to investigate the pharmacology subserving the behavioural impact of environmental stimuli, some of which we highlight. Subsequently, we examine whether the impact of drug-associated stimuli can be attenuated via a process of extinction, and how this question is addressed in the laboratory. We discuss how preclinical research has been translated into behavioural therapies targeting substance abuse, as well as highlight potential developments to therapies that might produce more enduring changes in behaviour.
Collapse
Affiliation(s)
- Christina J Perry
- Behavioural Neuroscience Division, The Florey Institute of Neuroscience and Mental HealthParkville, Vic., Australia
- Florey Department of Neuroscience and Mental Health, University of MelbourneParkville, Vic., Australia
| | - Isabel Zbukvic
- Behavioural Neuroscience Division, The Florey Institute of Neuroscience and Mental HealthParkville, Vic., Australia
- Florey Department of Neuroscience and Mental Health, University of MelbourneParkville, Vic., Australia
| | - Jee Hyun Kim
- Behavioural Neuroscience Division, The Florey Institute of Neuroscience and Mental HealthParkville, Vic., Australia
- Florey Department of Neuroscience and Mental Health, University of MelbourneParkville, Vic., Australia
| | - Andrew J Lawrence
- Behavioural Neuroscience Division, The Florey Institute of Neuroscience and Mental HealthParkville, Vic., Australia
- Florey Department of Neuroscience and Mental Health, University of MelbourneParkville, Vic., Australia
| |
Collapse
|
19
|
Samaha AN. Can antipsychotic treatment contribute to drug addiction in schizophrenia? Prog Neuropsychopharmacol Biol Psychiatry 2014; 52:9-16. [PMID: 23793001 DOI: 10.1016/j.pnpbp.2013.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 06/02/2013] [Accepted: 06/11/2013] [Indexed: 12/27/2022]
Abstract
Individuals with schizophrenia are at very high risk for drug abuse and addiction. Patients with a coexisting drug problem fare worse than patients who do not use drugs, and are also more difficult to treat. Current hypotheses cannot adequately account for why patients with schizophrenia so often have a co-morbid drug problem. I present here a complementary hypothesis based on evidence showing that chronic exposure to antipsychotic medications can induce supersensitivity within the brain's dopamine systems, and that this in turn can enhance the rewarding and incentive motivational effects of drugs and reward cues. At the neurobiological level, these effects of antipsychotics are potentially linked to antipsychotic-induced increases in the striatal levels of dopamine D2 receptors and D2 receptors in a high-affinity state for dopamine, particularly at postsynaptic sites. Antipsychotic-induced dopamine supersensitivity and enhanced reward function are not inevitable consequences of prolonged antipsychotic treatment. At least two parameters appear to promote these effects; the use of antipsychotics of the typical class, and continuous rather than intermittent antipsychotic exposure, such that silencing of dopaminergic neurotransmission via D2/3 receptors is unremitting. Thus, by inducing forms of neural plasticity that facilitate the ability of drugs and reward cues to gain control over behaviour, some currently used treatment strategies with typical antipsychotics might contribute to compulsive drug seeking and drug taking behaviours in vulnerable schizophrenia patients.
Collapse
Affiliation(s)
- Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada, H3C 3J7; CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada, H3C 3J7.
| |
Collapse
|
20
|
Dickson PE, Miller MM, Rogers TD, Blaha CD, Mittleman G. Effects of adolescent nicotine exposure and withdrawal on intravenous cocaine self-administration during adulthood in male C57BL/6J mice. Addict Biol 2014; 19:37-48. [PMID: 22978678 DOI: 10.1111/j.1369-1600.2012.00496.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Studies of adolescent drug use show (1) a pattern in which the use of tobacco precedes the use of other drugs and (2) a positive relationship between adolescent tobacco use and later drug use. These observations have led to the hypothesis that a causal relationship exists between early exposure to nicotine and the later use of hard drugs such as cocaine. Using male C57BL/6J mice, we tested the hypothesis that nicotine exposure in adolescence leads to increased intravenous self-administration (IVSA) of cocaine in adulthood. Using miniature osmotic pumps, we exposed mice and their littermate controls to nicotine (24 mg/kg/day) or vehicle, respectively, over the entire course of adolescence [postnatal days (P) 28-56]. Nicotine exposure was terminated on P56 and mice were not exposed to nicotine again during the experiment. On P73, mice were allowed to acquire cocaine IVSA (1.0 mg/kg/infusion) and a dose-response curve was generated (0.18, 0.32, 0.56, 1.0, 1.8 mg/kg/infusion). Lever pressing during extinction conditions was also evaluated. All mice rapidly learned to lever press for the combination of cocaine infusions and non-drug stimuli. Analysis of the dose-response curve revealed that adolescent nicotine-exposed mice self-administered significantly more (P < 0.05) cocaine than controls at all but the highest dose. No significant differences were observed between adolescent nicotine-exposed and control mice during the acquisition or extinction stages. These results indicate that adolescent nicotine exposure can increase cocaine IVSA in mice, which suggests the possibility of a causal link between adolescent tobacco use and later cocaine use in humans.
Collapse
Affiliation(s)
| | | | | | | | - Guy Mittleman
- Department of Psychology; University of Memphis; Memphis TN USA
| |
Collapse
|
21
|
Minogianis EA, Lévesque D, Samaha AN. The speed of cocaine delivery determines the subsequent motivation to self-administer the drug. Neuropsychopharmacology 2013; 38:2644-56. [PMID: 23921953 PMCID: PMC3828535 DOI: 10.1038/npp.2013.173] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 07/11/2013] [Accepted: 07/15/2013] [Indexed: 12/17/2022]
Abstract
The rapid delivery of drugs of abuse to the brain is associated with an increased likelihood and severity of addiction. Here we evaluated the hypothesis that rapidly delivered cocaine facilitates the addiction process by promoting the development of enhanced motivation for the drug. Rats lever-pressed for cocaine delivered intravenously over 5 or 90 s under fixed ratio (FR) during 6-h sessions. The motivation for cocaine was subsequently assessed using a progressive ratio (PR) schedule, where each successive drug injection cost an exponentially greater number of lever presses, until the cessation of responding. Throughout all self-administration sessions, all rats could only take one injection every 90 s. The 5-s groups self-administered more drug than the 90-s groups across the FR sessions. Under PR, animals that had chronically self-administered rapidly delivered cocaine took more cocaine across a range of doses and regardless of whether the drug was delivered over 5 or 90 s during PR testing. The speed of delivery also determined the long-term neurobiological impact of cocaine. Fourteen days following cocaine withdrawal, caudate-putamen D2 levels were decreased only in the 90-s rats, and quinpirole-mediated Gα(i/o)-protein activation was increased to a greater extent in the 90- vs 5-s rats. Thus, rapid delivery promotes the pursuit of cocaine in the face of rising costs and alters cocaine-induced changes in striatal D2 receptor number and function. As such, rapidly delivered cocaine might facilitate addiction because it more readily alters brain motivation circuits in ways that contribute to the compulsive pursuit of the drug.
Collapse
Affiliation(s)
- Ellie-Anna Minogianis
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,Department of Pharmacology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montreal, QC H3C 3J7, Canada, Tel: +514 343 6111 x. 32788, Fax: +514 343 2291, E-mail:
| |
Collapse
|
22
|
Saunders BT, Robinson TE. Individual variation in resisting temptation: implications for addiction. Neurosci Biobehav Rev 2013; 37:1955-75. [PMID: 23438893 PMCID: PMC3732519 DOI: 10.1016/j.neubiorev.2013.02.008] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/28/2013] [Accepted: 02/12/2013] [Indexed: 11/29/2022]
Abstract
When exposed to the sights, sounds, smells and/or places that have been associated with rewards, such as food or drugs, some individuals have difficulty resisting the temptation to seek out and consume them. Others have less difficulty restraining themselves. Thus, Pavlovian reward cues may motivate maladaptive patterns of behavior to a greater extent in some individuals than in others. We are just beginning to understand the factors underlying individual differences in the extent to which reward cues acquire powerful motivational properties, and therefore, the ability to act as incentive stimuli. Here we review converging evidence from studies in both human and non-human animals suggesting that a subset of individuals are more "cue reactive", in that certain reward cues are more likely to attract these individuals to them and motivate actions to get them. We suggest that those individuals for whom Pavlovian reward cues become especially powerful incentives may be more vulnerable to impulse control disorders, such as binge eating and addiction.
Collapse
Affiliation(s)
| | - Terry E. Robinson
- Department of Psychology (Biopsychology Program), University of Michigan
| |
Collapse
|
23
|
Bédard AM, Maheux J, Lévesque D, Samaha AN. Prior haloperidol, but not olanzapine, exposure augments the pursuit of reward cues: implications for substance abuse in schizophrenia. Schizophr Bull 2013; 39:692-702. [PMID: 22927669 PMCID: PMC3627770 DOI: 10.1093/schbul/sbs077] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Drug abuse and addiction are excessively common in schizophrenia. Chronic antipsychotic treatment might contribute to this comorbidity by inducing supersensitivity within the brain's dopamine system. Dopamine supersensitivity can enhance the incentive motivational properties of reward cues, and reward cues contribute to the maintenance and severity of drug addiction. We have shown previously that rats withdrawn from continuous haloperidol (HAL) treatment (via subcutaneous minipump) develop dopamine supersensitivity and pursue reward cues more vigorously than HAL-naive rats following an amphetamine (AMPH) challenge. Atypical antipsychotic drugs are thought to be less likely than typicals to produce dopamine supersensitivity. Thus, we compared the effects of HAL and the atypical antipsychotic olanzapine (OLZ) on the pursuit of reward cues. Rats were trained to associate a light-tone cue with water then treated with HAL or OLZ. Following antipsychotic withdrawal, we assessed AMPH-induced enhancement of lever pressing for the cue. Withdrawal from HAL, but not from OLZ, enhanced this effect. HAL, but not OLZ, also enhanced AMPH-induced psychomotor activation and c-fos mRNA expression in the caudate-putamen. Thus, prior HAL, but not OLZ, enhanced conditioned reward following an AMPH challenge, and this was potentially linked to enhanced behavioral sensitivity to AMPH and AMPH-induced engagement of the caudate-putamen. These findings suggest that HAL, but not an atypical like OLZ, modifies reward circuitry in ways that increase responsiveness to reward cues. Because enhanced responsiveness to reward cues can promote drug-seeking behavior, it should be investigated whether atypical antipsychotics might be a preferential option in schizophrenic patients at risk for drug abuse or addiction.
Collapse
Affiliation(s)
- Anne-Marie Bédard
- Department of Pharmacology, Faculty of Medicine, Université de MontréalMontreal, QC, Canada
| | - Jérôme Maheux
- Faculty of Pharmacy, Université de MontréalMontreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de MontréalMontreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de MontréalMontreal, QC, Canada; ,CNS Research Group, Faculty of Medicine, Université de MontréalMontreal, QC, Canada,To whom correspondence should be addressed; C.P. 6128, Succursale Centre-ville, Montreal, Quebec H3C 3J7, Canada; tel: 514-343-6111, ext. 32788, fax: 514-343-2291, e-mail:
| |
Collapse
|
24
|
Tunstall BJ, Verendeev A, Kearns DN. A comparison of therapies for the treatment of drug cues: counterconditioning vs. extinction in male rats. Exp Clin Psychopharmacol 2012; 20:447-53. [PMID: 23230857 PMCID: PMC3716831 DOI: 10.1037/a0030593] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although extinction has been used as a treatment to reduce the power of drug cues, a better method is needed. Research with traditional reinforcers has shown that counterconditioning--pairing an appetitive cue with an aversive stimulus--can suppress cue-controlled behavior. The present experiment compared the counterconditioning and extinction of cocaine cues. Male rats were first trained to self-administer cocaine during a light cue. In the second phase, the light was paired with footshock in the counterconditioning group. The extinction group was treated similarly, except light presentations did not end in footshock. Counterconditioning suppressed cocaine seeking to a greater extent than extinction while the counterconditioning treatment was actively administered. On a subsequent stimulus compounding test, where footshock was discontinued and the light was presented simultaneously with an untreated cocaine cue (a tone), suppressive effects of counterconditioning were evident during the early portion of the test but not during later trials. Overall, results of the present experiment suggest that counterconditioning produces only temporarily suppressive effects on cue-controlled cocaine seeking. Methods for directly weakening the cue-drug association (e.g., "deepened extinction") may prove to be more useful drug cue treatments.
Collapse
Affiliation(s)
- Brendan J. Tunstall
- corresponding author: Brendan J. Tunstall, Psychology Department, American University, 4400 Massachusetts Ave NW, Washington, DC 20016, , Phone: 202-885-1725, FAX: 202-885-1023
| | | | | |
Collapse
|
25
|
de Wit H, Phillips TJ. Do initial responses to drugs predict future use or abuse? Neurosci Biobehav Rev 2012; 36:1565-76. [PMID: 22542906 PMCID: PMC3372699 DOI: 10.1016/j.neubiorev.2012.04.005] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 03/09/2012] [Accepted: 04/12/2012] [Indexed: 10/28/2022]
Abstract
Individuals vary in their initial reactions to drugs of abuse in ways that may contribute to the likelihood of subsequent drug use. In humans, most drugs of abuse produce positive subjective states such as euphoria and feelings of well-being, which may facilitate repeated use. In nonhumans, many drugs initially increase locomotor activity and produce discriminative stimulus effects, both of which have been considered to be models of human stimulant and subjective states. Both humans and nonhumans vary in their sensitivity to early acute drug effects in ways that may predict future use or self-administration, and some of these variations appear to be genetic in origin. However, it is not known exactly how the initial responses to drugs in either humans or nonhumans relate to subsequent use or abuse. In humans, positive effects of drugs facilitate continued use of a drug while negative effects discourage use, and in nonhumans, greater genetic risk for drug intake is predicted by reduced sensitivity to drug aversive effects; but whether these initial responses affect escalation of drug use, and the development of dependence is currently unknown. Although early use of a drug is a necessary step in the progression to abuse and dependence, other variables may be of greater importance in the transition from use to abuse. Alternatively, the same variables that predict initial acute drug effects and early use may significantly contribute to continued use, escalation and dependence. Here we review the existing evidence for relations between initial direct drug effects, early use, and continued use. Ultimately, these relations can only be determined from systematic longitudinal studies with comprehensive assessments from early drug responses to progression of problem drug use. In parallel, additional investigation of initial responses in animal models as predictors of drug use will shed light on the underlying mechanisms.
Collapse
Affiliation(s)
- Harriet de Wit
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, 5841 S Maryland Ave, MC3077, Chicago, IL 60637, United States.
| | | |
Collapse
|
26
|
Compound stimulus presentation and the norepinephrine reuptake inhibitor atomoxetine enhance long-term extinction of cocaine-seeking behavior. Neuropsychopharmacology 2012; 37:975-85. [PMID: 22089320 PMCID: PMC3280649 DOI: 10.1038/npp.2011.281] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Drug abstinence is frequently compromised when addicted individuals are re-exposed to environmental stimuli previously associated with drug use. Research with human addicts and in animal models has demonstrated that extinction learning (non-reinforced cue-exposure) can reduce the capacity of such stimuli to induce relapse, yet extinction therapies have limited long-term success under real-world conditions (Bouton, 2002; O'Brien, 2008). We hypothesized that enhancing extinction would reduce the later ability of drug-predictive cues to precipitate drug-seeking behavior. We, therefore, tested whether compound stimulus presentation and pharmacological treatments that augment noradrenergic activity (atomoxetine; norepinephrine reuptake inhibitor) during extinction training would facilitate the extinction of drug-seeking behaviors, thus reducing relapse. Rats were trained that the presentation of a discrete cue signaled that a lever press response would result in cocaine reinforcement. Rats were subsequently extinguished and spontaneous recovery of drug-seeking behavior following presentation of previously drug-predictive cues was tested 4 weeks later. We find that compound stimulus presentations or pharmacologically increasing noradrenergic activity during extinction training results in less future recovery of responding, whereas propranolol treatment reduced the benefit seen with compound stimulus presentation. These data may have important implications for understanding the biological basis of extinction learning, as well as for improving the outcome of extinction-based therapies.
Collapse
|
27
|
Cues paired with either rapid or slower self-administered cocaine injections acquire similar conditioned rewarding properties. PLoS One 2011; 6:e26481. [PMID: 22039496 PMCID: PMC3198427 DOI: 10.1371/journal.pone.0026481] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022] Open
Abstract
The faster drugs of abuse reach the brain, the more addictive they can be. It is not known why this is. Environmental stimuli associated with drugs can promote the development and persistence of addiction by invigorating and precipitating drug-seeking behaviour. We determined, therefore, whether cues associated with the self-administration of rapidly delivered cocaine (injected intravenously over 5 versus 90 seconds) would acquire greater conditioned rewarding properties, as assessed by the performance of an operant response reinforced solely by the cues. Rats nose-poked for intravenous cocaine infusions delivered either over 5 or 90 seconds. Discrete visual cues accompanied each infusion. The rats could then press a lever to obtain the cues—now a conditioned reward—or an inactive lever. Rats in both the 5- and 90-second groups pressed more on the active versus inactive lever following extensive (24 sessions) but not following limited (3 sessions) self-administration training. There were no group differences in this behaviour. Following withdrawal from cocaine self-administration, lever discrimination progressively abated in both groups and was lost by withdrawal day 30. However, the rewarding properties of the cues were not “forgotten” because on withdrawal days 32–33, amphetamine selectively enhanced active-lever pressing, and did so to a similar extent in both groups. Thus, cues paired with rapid or slower cocaine delivery acquire similar conditioned rewarding properties. We conclude, therefore, that the rapid delivery of cocaine to the brain promotes addiction by mechanisms that might not involve a greater ability of drug cues to control behaviour.
Collapse
|
28
|
Anker JJ, Carroll ME. Adolescent nicotine exposure sensitizes cue-induced reinstatement of cocaine seeking in rats bred for high and low saccharin intake. Drug Alcohol Depend 2011; 118:68-72. [PMID: 21439737 DOI: 10.1016/j.drugalcdep.2011.02.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 01/11/2011] [Accepted: 02/20/2011] [Indexed: 01/25/2023]
Abstract
BACKGROUND Environmental factors such as early drug exposure influence drug abuse vulnerability, and evidence also suggests that drug abuse is highly heritable. The purpose of the present study was to determine whether environmental and genetic factors interact to produce additive drug abuse vulnerability. METHODS An animal model of relapse was used to examine the effects of adolescent nicotine exposure on adult cocaine seeking in rats bred for high (HiS) and low (LoS) saccharin intake. Rats from HiS and LoS progenitor lines received s.c. injections of nicotine for 10 days (postnatal days 22-31). Rats were then allowed to reach adulthood and were trained to lever press for cocaine infusions. During each self-administration session, the house light (HL) was illuminated and each lever press activated a set of lights adjacent to the lever (LL). Following cocaine self-administration, the HL and LL were deactivated, cocaine solutions were replaced with saline, and rats extinguished lever pressing. Subsequently, rats were tested under a multi-component reinstatement procedure consisting of: (1) cue-induced reinstatement with LL alone and the HL presented alone, (2) cocaine-induced reinstatement without LL and HL present, (3) and cocaine-induced reinstatement with LL present. RESULTS The results indicated that adolescent nicotine exposure sensitized the reinstatement of cocaine seeking during adulthood in HiS (but not LoS) rats when lever pressing resulted in LL cue presentations. In addition, following administration of the cocaine priming injection, rats exposed to nicotine (vs. saline) during adolescence (LoS and HiS) engaged in more cocaine seeking under the cocaine-primed reinstatement condition when lever pressing illuminated the LL. CONCLUSION These results suggest that drug abuse vulnerability may be a function of early life exposure to drugs of abuse in addition to genetic influences.
Collapse
Affiliation(s)
- Justin J Anker
- Department of Psychiatry, University of Minnesota, MMC 392, Minneapolis, MN 55455, USA.
| | | |
Collapse
|
29
|
Schindler CW, Cogan ES, Thorndike EB, Panlilio LV. Rapid delivery of cocaine facilitates acquisition of self-administration in rats: an effect masked by paired stimuli. Pharmacol Biochem Behav 2011; 99:301-6. [PMID: 21600912 PMCID: PMC3129474 DOI: 10.1016/j.pbb.2011.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022]
Abstract
In general, faster infusions of cocaine are more likely to support behavior related to abuse than are slower infusions. However, some studies of cocaine self-administration in rats have failed to support this finding, possibly because the effect was masked by other factors. One such factor may be the pairing of a stimulus with the infusion, a procedure that is known to facilitate acquisition of drug self-administration. We compared fast and slow infusions by allowing groups of rats to acquire cocaine self-administration at a dose of 1mg/kg/infusion, delivered over different durations (1.8 or 100 s). Two groups were trained with either short or long infusions paired with a visual stimulus change (lights off), and two other groups were trained with short or long durations but with no stimulus change. Both groups trained with a paired stimulus acquired cocaine self-administration. With no stimulus change, the rats trained with the 1.8-s infusion acquired cocaine self-administration at a rate comparable to the two groups that were trained with a paired stimulus. However, most rats in the group trained with the 100-s infusion that was not accompanied by a stimulus change failed to acquire cocaine self-administration. The stimulus itself did not support responding. These results indicate that infusing a given dose of cocaine over a longer duration reduces its ability to support self-administration, but drug-paired stimuli can partially mask this effect by enhancing the effectiveness of slow infusions.
Collapse
Affiliation(s)
- Charles W Schindler
- Preclinical Pharmacology Section, Behavioral Neuroscience Branch, DHHS/NIH/NIDA Intramural Research Program, 251 Bayview Blvd., Suite 200, Baltimore, MD 21224, USA.
| | | | | | | |
Collapse
|
30
|
Bédard AM, Maheux J, Lévesque D, Samaha AN. Continuous, but not intermittent, antipsychotic drug delivery intensifies the pursuit of reward cues. Neuropsychopharmacology 2011; 36:1248-59. [PMID: 21326191 PMCID: PMC3079837 DOI: 10.1038/npp.2011.10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chronic exposure to antipsychotic medications can persistently change brain dopamine systems. Most studies on the functional significance of these neural changes have focused on motor behavior and few have addressed how long-term antipsychotic treatment might influence dopamine-mediated reward function. We asked, therefore, whether a clinically relevant antipsychotic treatment regimen would alter the incentive motivational properties of a reward cue. We assessed the ability of a Pavlovian-conditioned stimulus to function as a conditioned reward, as well as to elicit approach behavior in rats treated with haloperidol, either continuously (achieved via subcutaneous osmotic minipump) or intermittently (achieved via daily subcutaneous injections). Continuous, but not intermittent, treatment enhanced the ability of amphetamine to potentiate the conditioned reinforcing effects of a cue associated with water. This effect was not related to differences in the ability to attribute predictive value to a conditioned stimulus (as measured by conditioned approach behavior), but was potentially linked to the development of behavioral supersensitivity to amphetamine and to augmented amphetamine-induced immediate early-gene expression (c-fos and Nur77) in dorsal striatopallidal and striatonigral cells. By enhancing the ability of reward cues to control behavior and by intensifying dopamine-mediated striatopallidal and striatonigral cell activity, standard (ie, continuous) antipsychotic treatment regimens might exacerbate drug-seeking and drug-taking behavior in schizophrenia. Achieving regular but transiently high antipsychotic levels in the brain (as modeled in the intermittent condition) might be a viable option to prevent these changes. This possibility should be explored in the clinic.
Collapse
Affiliation(s)
- Anne-Marie Bédard
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Jérôme Maheux
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Daniel Lévesque
- Faculty of Pharmacy, Université de Montréal, Montreal, QC, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,CNS Research Group, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada,Department of Pharmacology, Faculty of Medicine, Université de Montréal, C P 6128, Succursale Centre-ville, Montreal, QC, Canada H3C 3J7. Tel: +1 514 343 6111; Fax: +1 514 343 2291; E-mail:
| |
Collapse
|
31
|
|
32
|
Cocaine deprivation effect: cue abstinence over weekends boosts anticipatory 50-kHz ultrasonic vocalizations in rats. Behav Brain Res 2010; 214:75-9. [PMID: 20470830 DOI: 10.1016/j.bbr.2010.04.057] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/30/2010] [Accepted: 04/30/2010] [Indexed: 11/22/2022]
Abstract
In drug dependence studies, rats are often tested daily with short breaks (such as weekends) spent untested in their home cages. Research on alcohol models has suggested that breaks from continuous testing can transiently enhance self-administration (termed the "alcohol deprivation effect"). The present study explored whether the salience of cocaine-access cues is increased after skipping weekend cocaine and cue exposures. Ultrasonic vocalizations (USVs) of the 50-kHz class are emitted by rats exposed to intravenous cocaine and have been shown to increase with repeated drug exposure at the same dose level (sensitization). The present study found that over the course of several weeks of cocaine self- or yoked-administration pre-drug cues signaling forthcoming access or delivery of cocaine elicited marked amounts of anticipatory 50-kHz USVs, and that weekend deprivation from cues and cocaine exaggerated further the level of calling (more calls on Mondays compared to Fridays). Anticipatory USVs extinguished less rapidly when weekend access to unreinforced cues was denied. The results may have clinical implications, in that intermittently avoiding cues or context may enhance drug cue salience and resistance to extinction.
Collapse
|
33
|
Saunders BT, Robinson TE. A cocaine cue acts as an incentive stimulus in some but not others: implications for addiction. Biol Psychiatry 2010; 67:730-6. [PMID: 20045508 PMCID: PMC2849872 DOI: 10.1016/j.biopsych.2009.11.015] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 11/11/2009] [Accepted: 11/14/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND In addicts drug cues attract attention, elicit approach, and motivate drug-seeking and drug-taking behavior, and addicts find it difficult to resist such cues. In preclinical studies we have found, however, that food cues acquire incentive motivational properties only in a subset of individuals. For example, a food cue becomes attractive, eliciting approach and engagement with it, and acts as an effective conditional reinforcer in some rats but not others. We asked, therefore, whether rats that have a propensity to attribute incentive salience to a food cue are the same ones that attribute incentive value to a drug (cocaine) cue. METHODS We first used a Pavlovian conditioned approach procedure to determine which individual rats attributed incentive salience to a food cue. A second cue was then associated with the IV self-administration of cocaine. Later, the ability of the cocaine cue to maintain self-administration behavior and to reinstate self-administration after extinction was assessed. RESULTS We report that in individuals that had a propensity to attribute incentive salience to a food cue, a cocaine cue spurred motivation to take drugs (its removal greatly diminished self-administration) and reinstated robust drug-seeking after extinction. However, in those individuals that failed to attribute incentive salience to a food cue, the cocaine cue was relatively devoid of incentive motivational properties. CONCLUSIONS We conclude that it is possible to determine, before any drug experience, which individuals will most likely have difficulty resisting drug cues, a trait that might confer susceptibility to addiction.
Collapse
Affiliation(s)
| | - Terry E. Robinson
- To whom correspondence should be addressed: , Voice: 1 734-763-4361, Fax: 1 734-763-7480
| |
Collapse
|
34
|
Ma ST, Maier EY, Ahrens AM, Schallert T, Duvauchelle CL. Repeated intravenous cocaine experience: development and escalation of pre-drug anticipatory 50-kHz ultrasonic vocalizations in rats. Behav Brain Res 2010; 212:109-14. [PMID: 20382187 DOI: 10.1016/j.bbr.2010.04.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/30/2010] [Accepted: 04/01/2010] [Indexed: 10/19/2022]
Abstract
Ultrasonic vocalization (USV) in the 50-kHz range occurs in rats immediately upon first-time exposure to cocaine or amphetamine, and rapidly increases with repetitive drug exposure at the same dose. This sensitized positive-affect response to these drugs of abuse is persistent in that the peak level of USVs again appears when the drug is reintroduced after several weeks of drug discontinuation. The present study explored whether with enough experience USVs might be elicited, and gradually escalate, in anticipation of impending drug delivery. Rats were trained to self-administer (SA) cocaine intravenously by lever pressing 5 days per week for 4 weeks. Yoked rats received experimenter-delivered cocaine matching that of SA rats. USVs and locomotor activity were recorded during each 10-min period prior to 60-min drug access sessions. Extinction trials in which drug access was denied were then carried out over an additional 4-week period. After about a week of cocaine experience, both the SA and yoked groups began to progressively increase USVs when placed in an environment that predicted forthcoming drug exposure. Extinction of anticipatory calls and locomotion occurred over days after drug access ended. USVs may be a useful model for specifically investigating the neural basis of drug anticipation and aid in developing and assessing new addiction treatment strategies for reducing craving and relapse.
Collapse
Affiliation(s)
- Sean T Ma
- Department of Psychology and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
| | | | | | | | | |
Collapse
|
35
|
Grakalic I, Panlilio LV, Quiroz C, Schindler CW. Effects of orbitofrontal cortex lesions on cocaine self-administration. Neuroscience 2010; 165:313-24. [PMID: 19879927 DOI: 10.1016/j.neuroscience.2009.10.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/22/2009] [Accepted: 10/23/2009] [Indexed: 11/24/2022]
Abstract
Previous research has implicated limbic and prefrontal cortical areas in the control of drug-seeking behavior. The present study examined the effects of orbitofrontal-cortex (OFC) lesions on acquisition, dose-dependence, within-session patterning, and reinstatement of cocaine self-administration. Rats received OFC or sham lesions before or after acquisition (0.3 mg/kg/injection, paired with a visual stimulus), then were tested with a range of doses (0, 0.03, 0.1, 0.3 and 1). Compared to controls, rats lesioned before acquisition acquired the behavior sooner, responded more at low doses, and responded more on the first day of extinction. Rats that were lesioned after acquisition showed an even larger increase in responding (approximately 250%) at the lowest dose, and they also showed increased timeout responding and drug "loading" at low doses. Pre-acquisition lesions were tested and found to have no effect on cocaine-induced reinstatement. In parallel experiments examining effects of pre-acquisition OFC lesions on food-reinforced responding, lesions did not alter acquisition, maintenance, or reinstatement, but accelerated the course of extinction. The increased cocaine self-administration seen in OFC-lesioned rats did not resemble the dysregulated drug intake observed in long-access models of addiction but might be due to impaired response inhibition or impaired tracking of the reward value of drug-related cues.
Collapse
Affiliation(s)
- I Grakalic
- DHHS/NIH/NIDA Intramural Research Program, Baltimore, MD, USA.
| | | | | | | |
Collapse
|
36
|
Schindler CW, Panlilio LV, Thorndike EB. Effect of rate of delivery of intravenous cocaine on self-administration in rats. Pharmacol Biochem Behav 2009; 93:375-81. [PMID: 19464316 DOI: 10.1016/j.pbb.2009.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 05/12/2009] [Accepted: 05/17/2009] [Indexed: 10/20/2022]
Abstract
Many studies of drug self-administration in primates have shown that faster infusions of a drug are more reinforcing than slower infusions. Similar effects have not been shown in rats. We assessed the influence of delivery rate by allowing rats to choose between the same doses of intravenous cocaine delivered over two different infusion speeds. Rats were trained in chambers containing two nose-poke response devices. In Experiment 1, responses in one nose-poke delivered 0.3 mg/kg/injection of cocaine over 10 s, and responses in the other delivered the same dose over 100 s. In Experiment 2, the same procedure was used, but with 1.0 mg/kg/injection dose delivered over 1.7 versus 100 s. During acquisition, most rats preferred the faster infusion. When the delivery rates associated with the nose pokes were reversed, rats trained with 0.3 mg/kg/injection failed to switch nose-poke preference, but half the rats trained with 1.0 mg/kg/injection did switch. In Experiment 3, the choice was between 1 mg/kg cocaine delivered over 1.7 s and no reinforcement. Here, rats quickly learned to respond in the nose-poke associated with cocaine and quickly switched their choice during reversal. In Experiment 4, two groups of rats were allowed to choose between food delivered with a delay of 1 versus 5 s or 1 versus 10 s, respectively. Rats preferred the shorter delay during initial training. In reversal, some rats in the 1 vs 5 s group failed to reverse, while all the rats in the 1 vs 10 s group reversed. These results show that faster infusions of cocaine are clearly more reinforcing during acquisition, but delivery rate may not be as important to the maintenance of self-administration once it has been established. The results with food suggest that these findings represent general principles of behavior and are not unique to drug self-administration.
Collapse
Affiliation(s)
- Charles W Schindler
- Preclinical Pharmacology Section, Behavioral Neuroscience Branch, DHHS/NIH/NIDA Intramural Research Program, Baltimore, MD 21224, United States.
| | | | | |
Collapse
|
37
|
Panlilio LV, Thorndike EB, Schindler CW. A stimulus-control account of dysregulated drug intake. Pharmacol Biochem Behav 2009; 92:439-47. [PMID: 19463257 DOI: 10.1016/j.pbb.2009.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 12/12/2008] [Accepted: 01/16/2009] [Indexed: 11/19/2022]
Abstract
Drug self-administration typically occurs in a regular temporal pattern, with a consistent pause following each injection. We have proposed that this patterning results from differential reinforcement of post-injection pausing. In this view, even when every response produces an injection, some injections are not reinforcing because they occur when the level of drug effect is already maximal; consequently, drug reinforcement occurs on an intermittent schedule, and the interoceptive drug effect functions as a cue, indicating when another injection will be reinforcing. Previously, we emulated this situation with rats by using food reinforcement; each response was recorded as delivering a "virtual" injection, and a visual cue tracked the virtual drug level to indicate availability of reinforcement. This emulation schedule produced response patterns strikingly similar to actual drug self-administration. In the present study, the emulation schedule was modified to determine whether reinforcement of pausing is sufficient to produce these patterns, or whether a cue is necessary. Without a cue, response patterns were irregular and virtual drug intake was escalated. These results suggest that a failure of interoceptive cues to control pausing might contribute to the dysregulated drug intake that is associated with addiction.
Collapse
Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, 251 Bayview Blvd, Baltimore, MD 21224, USA.
| | | | | |
Collapse
|
38
|
Lombas AS, Kearns DN, Weiss SJ. DIFFERENTIAL EFFECTS OF A FOOD-BASED CONDITIONED INHIBITOR ON FOOD- OR COCAINE-SEEKING BEHAVIOR. LEARNING AND MOTIVATION 2008; 39:323-333. [PMID: 19885370 DOI: 10.1016/j.lmot.2008.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present experiment compared the effects of a food-based conditioned inhibitor on food seeking vs. cocaine seeking behavior. In two groups of rats, the A+/AB- Pavlovian conditioned inhibition procedure was used to create a conditioned inhibitor for food. Then, for one group of rats (Food-Food Group), a click stimulus was established as an operant discriminative stimulus (S(D)) for food-reinforced lever pressing. In the other group (Food-Cocaine Group), the click was established as an S(D) for cocaine self-administration. In testing, the putative inhibitor for food was simultaneously presented with the click for the first time in both groups. In the Food-Food Group, the food-based inhibitor suppressed responding occasioned by the click significantly more than did a neutral control stimulus. In contrast, in the Food-Cocaine Group, there was no difference in the amount of suppression produced by the food-based inhibitor and the control stimulus. These results suggest that the effects of food-based Pavlovian conditioned inhibitors are specific for food-motivated behavior and do not easily transfer to cocaine-motivated behavior.
Collapse
Affiliation(s)
- Andrés S Lombas
- Facultad de Psicología, Universidad del País Vasco, Avenida de Tolosa, 70, 20018 San Sebastián, Spain
| | | | | |
Collapse
|
39
|
Christensen CJ, Silberberg A, Hursh SR, Roma PG, Riley AL. Demand for cocaine and food over time. Pharmacol Biochem Behav 2008; 91:209-16. [PMID: 18692088 DOI: 10.1016/j.pbb.2008.07.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 07/09/2008] [Accepted: 07/11/2008] [Indexed: 11/17/2022]
Abstract
When reinterpreted, data from Ahmed and Koob [Ahmed, S.H., Koob, G.F., Transition from moderate to excessive drug intake: Change in hedonic set point. Science 1998; 282:298-301.] show that the reinforcing strength of cocaine, an inessential good, increases with experience. However, no such effect obtains with a homeostatically regulated good such as food. The present study evaluated whether this difference could serve to distinguish abused drugs from biologically necessary goods. In Experiment 1, five rats from Christensen, Silberberg, Hursh, Huntsberry and Riley [Christensen, C.J., Silberberg, A., Hursh, S.R., Huntsberry, M.E., Riley, A.L., Essential value of cocaine and food in rats: tests of the exponential model of demand. Psychopharmacology 2008;198(2):221-229.] earned cocaine under a Fixed-Ratio 3 schedule for 7 sessions. Thereafter, in a demand procedure identical to that in Christensen et al., demand was re-assessed by measuring consumption at Fixed Ratios between 3 and 560. In Experiment 2, five different rats from Christensen et al. had their food demand curves re-determined using an identical procedure as the first. When fit with the exponential model, the second determination of cocaine demand in Experiment 1 showed greater essential value than the first, indicating that strength increased with cocaine exposure. In Experiment 2, the re-determined food demand curves showed no change from their initial determination. These results show that the strength of cocaine, but not food, increases with increased experience. Measures of time-based changes in essential value may serve as a basis for distinguishing addictive from non-addictive reinforcers.
Collapse
|
40
|
Christensen CJ, Silberberg A, Hursh SR, Huntsberry ME, Riley AL. Essential value of cocaine and food in rats: tests of the exponential model of demand. Psychopharmacology (Berl) 2008; 198:221-9. [PMID: 18351323 DOI: 10.1007/s00213-008-1120-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2007] [Accepted: 02/18/2008] [Indexed: 11/25/2022]
Abstract
RATIONALE To provide a prospective test of the predictive adequacy of the exponential model of demand (Hursh and Silberberg, Psych Rev 115(1):186-198, 2008). OBJECTIVES In Experiment 1, to measure the 'essential value' (the propensity to defend consumption with changes in price) of cocaine and food in a demand analysis (functional relation between price and consumption) by means of the exponential model; in Experiment 2, to test whether the model's systematic underestimation of cocaine consumption in Experiment 1 was due to weight loss; and in Experiment 3, to evaluate the effects of cocaine on the essential value of food. MATERIALS AND METHODS In Experiment 1, demand curves for food and cocaine were determined by measuring consumption of these goods in a multiple schedule over a range of fixed ratios; in Experiment 2, a demand curve for only cocaine was determined; and in Experiment 3, demand for food was determined in the absence of cocaine. RESULTS In Experiment 1, the exponential equation accommodated high portions of variance for both curves, but systematically underestimated cocaine demand; in Experiment 2, this predictive underestimation of the equation was eliminated; and in Experiment 3, the essential value of food was greater than in Experiment 1. CONCLUSIONS The exponential model of demand accommodated the data variance for all cocaine and food demand curves. Compared to food, cocaine is a good of lower essential value.
Collapse
Affiliation(s)
- Chesley J Christensen
- Department of Psychology, American University, 4400 Massachusetts Ave., NW, Washington, DC 20016, USA.
| | | | | | | | | |
Collapse
|
41
|
Tomie A, Grimes KL, Pohorecky LA. Behavioral characteristics and neurobiological substrates shared by Pavlovian sign-tracking and drug abuse. BRAIN RESEARCH REVIEWS 2008; 58:121-35. [PMID: 18234349 PMCID: PMC2582385 DOI: 10.1016/j.brainresrev.2007.12.003] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 11/07/2007] [Accepted: 12/08/2007] [Indexed: 11/18/2022]
Abstract
Drug abuse researchers have noted striking similarities between behaviors elicited by Pavlovian sign-tracking procedures and prominent symptoms of drug abuse. In Pavlovian sign-tracking procedures, repeated paired presentations of a small object (conditioned stimulus, CS) with a reward (unconditioned stimulus, US) elicits a conditioned response (CR) that typically consists of approaching the CS, contacting the CS, and expressing consummatory responses at the CS. Sign-tracking CR performance is poorly controlled and exhibits spontaneous recovery and long-term retention, effects that resemble relapse. Sign-tracking resembles psychomotor activation, a syndrome of behavioral responses evoked by addictive drugs, and the effects of sign-tracking on corticosterone levels and activation of dopamine pathways resemble the neurobiological effects of abused drugs. Finally, the neurobiological profile of individuals susceptible to sign-tracking resembles the pathophysiological profile of vulnerability to drug abuse, and vulnerability to sign-tracking predicts vulnerability to impulsive responding and alcohol self-administration. Implications of sign-tracking for models of drug addiction are considered.
Collapse
Affiliation(s)
- Arthur Tomie
- Department of Psychology, Rutgers University, New Brunswick, NJ 08903, USA.
| | | | | |
Collapse
|
42
|
Abstract
RATIONALE To provide a prospective test of the predictive adequacy of the exponential model of demand (Hursh and Silberberg, Psych Rev 115(1):186-198, 2008). OBJECTIVES In Experiment 1, to measure the 'essential value' (the propensity to defend consumption with changes in price) of cocaine and food in a demand analysis (functional relation between price and consumption) by means of the exponential model; in Experiment 2, to test whether the model's systematic underestimation of cocaine consumption in Experiment 1 was due to weight loss; and in Experiment 3, to evaluate the effects of cocaine on the essential value of food. MATERIALS AND METHODS In Experiment 1, demand curves for food and cocaine were determined by measuring consumption of these goods in a multiple schedule over a range of fixed ratios; in Experiment 2, a demand curve for only cocaine was determined; and in Experiment 3, demand for food was determined in the absence of cocaine. RESULTS In Experiment 1, the exponential equation accommodated high portions of variance for both curves, but systematically underestimated cocaine demand; in Experiment 2, this predictive underestimation of the equation was eliminated; and in Experiment 3, the essential value of food was greater than in Experiment 1. CONCLUSIONS The exponential model of demand accommodated the data variance for all cocaine and food demand curves. Compared to food, cocaine is a good of lower essential value.
Collapse
|
43
|
Panlilio LV, Thorndike EB, Schindler CW. A stimulus-control account of regulated drug intake in rats. Psychopharmacology (Berl) 2008; 196:441-50. [PMID: 17957355 PMCID: PMC2699897 DOI: 10.1007/s00213-007-0978-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Accepted: 10/01/2007] [Indexed: 10/22/2022]
Abstract
RATIONALE Patterns of drug self-administration are often highly regular, with a consistent pause after each self-injection. This pausing might occur because the animal has learned that additional injections are not reinforcing once the drug effect has reached a certain level, possibly due to the reinforcement system reaching full capacity. Thus, interoceptive effects of the drug might function as a discriminative stimulus, signaling when additional drug will be reinforcing and when it will not. OBJECTIVE This hypothetical stimulus control aspect of drug self-administration was emulated using a schedule of food reinforcement. MATERIALS AND METHODS Rats' nose-poke responses produced food only when a cue light was present. No drug was administered at any time. However, the state of the light stimulus was determined by calculating what the whole-body drug level would have been if each response in the session had produced a drug injection. The light was only presented while this virtual drug level was below a specific threshold. A range of doses of cocaine and remifentanil were emulated using parameters based on previous self-administration experiments. RESULTS Response patterns were highly regular, dose-dependent, and remarkably similar to actual drug self-administration. CONCLUSION This similarity suggests that the emulation schedule may provide a reasonable model of the contingencies inherent in drug reinforcement. Thus, these results support a stimulus control account of regulated drug intake in which rats learn to discriminate when the level of drug effect has fallen to a point where another self-injection will be reinforcing.
Collapse
|
44
|
Abstract
AIM To review briefly the methods, assumptions, models, accomplishments, drawbacks and future directions of research using drug self-administration in animals and humans. BACKGROUND The use of drug self-administration to study addiction is based on the assumption that drugs reinforce the behavior that results in their delivery. A wide range of drug self-administration techniques have been developed to model specific aspects of addiction. These techniques are highly amenable to being combined with a wide variety of neuroscience techniques. CONCLUSIONS The identification of drug use as behavior that is reinforced by drugs has contributed greatly to the understanding and treatment of addiction. As part of a program of pre-clinical research that also involves screening with a variety of simpler behavioral techniques, drug self-administration procedures can provide an important last step in testing potential treatments for addiction. There is currently a concerted effort to develop self-administration procedures that model the extreme nature of the behavior engendered by addiction. As advances continue to be made in neuroscience techniques, self-administration should continue to provide a means of applying these techniques within a sophisticated and valid model of human drug addiction.
Collapse
Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, Baltimore, MD 21224, USA
| | | |
Collapse
|
45
|
Grakalic I, Panlilio LV, Thorndike EB, Schindler CW. Differential involvement of dopamine receptors in conditioned suppression induced by cocaine. Eur J Pharmacol 2007; 573:116-23. [PMID: 17628537 PMCID: PMC2039925 DOI: 10.1016/j.ejphar.2007.06.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 06/15/2007] [Accepted: 06/18/2007] [Indexed: 11/23/2022]
Abstract
Cocaine-paired stimuli can suppress food-reinforced operant behavior in rats, providing an animal model of conditioned drug effects. To study the neuropharmacological basis of this phenomenon, we examined the effects of various dopamine receptor antagonists on the acquisition and expression of cocaine-induced conditioned suppression in rats. Superimposed on an ongoing baseline of food-reinforced operant responding, a stimulus was paired with response-independent cocaine (3.0 mg/kg, i.v.) during each of 8 training sessions. To study acquisition, independent groups of rats were given saline, the dopamine D(1)-like receptor antagonist R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH 23390) (0.001-0.03 mg/kg, i.p.), or the dopamine D(2)-like receptor antagonist eticlopride (0.001-0.03 mg/kg, i.p.) prior to each training session. To study expression, independent groups of rats were trained first, then given saline, SCH 23390, eticlopride, or N-[4-(4-(2-methoxyphenyl)piperazinyl)butyl]-2-naphthamide (BP 897) (a dopamine D(3) partial receptor agonist; 0.1-1.0 mg/kg, i.p.) before test sessions in which the stimulus was presented without cocaine. Pre-treatment with either SCH 23390 or eticlopride during acquisition reduced the direct suppressant effects of cocaine, but conditioning was blocked only in rats that were treated with SCH 23390 during acquisition training. Expression of conditioning was attenuated only by eticlopride. Thus, dopamine at least partially mediates both the acquisition and expression of cocaine-induced conditioned suppression, with activation of dopamine D(1)- and D(2)-like receptors underlying these respective processes.
Collapse
MESH Headings
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Benzazepines/administration & dosage
- Benzazepines/pharmacology
- Cocaine/administration & dosage
- Cocaine/pharmacology
- Conditioning, Operant/drug effects
- Conditioning, Psychological/drug effects
- Dopamine D2 Receptor Antagonists
- Dose-Response Relationship, Drug
- Injections, Intraperitoneal
- Injections, Intravenous
- Learning/drug effects
- Male
- Piperazines/administration & dosage
- Piperazines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Dopamine/physiology
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/physiology
- Receptors, Dopamine D2/physiology
- Receptors, Dopamine D3/agonists
- Receptors, Dopamine D3/physiology
- Salicylamides/administration & dosage
- Salicylamides/pharmacology
Collapse
Affiliation(s)
- Ivana Grakalic
- Neuroscience Research Branch, Preclinical Pharmacology Section, Intramural Research Program, National Institute on Drug Abuse, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
| | | | | | | |
Collapse
|
46
|
Cohn SI, Weiss SJ. Stimulus control and compounding with ambient odor as a discriminative stimulus on a free-operant baseline. J Exp Anal Behav 2007; 87:261-73. [PMID: 17465315 PMCID: PMC1832170 DOI: 10.1901/jeab.2007.35-06] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Previous experiments have demonstrated that the simultaneous presentation of independently established discriminative stimuli can control rates of operant responding substantially higher than the rates occasioned by the individual stimuli. This "additive summation" phenomenon has been shown with a variety of different reinforcers (e.g., food, water, shock avoidance, cocaine, and heroin). Discriminative stimuli previously used in such studies have been limited to the visual and auditory sensory modalities. The present experiment sought to (1) establish stimulus control on a free-operant baseline with an ambient olfactory discriminative stimulus, (2) compare olfactory control to that produced with an auditory discriminative stimulus, and (3) determine whether compounding independently established olfactory and auditory discriminative stimuli produces additive summation. Rats lever pressed for food on a variable-interval schedule in the presence of either a tone or an odor, with comparable control developed to each stimulus. In the absence of these stimuli responding was not reinforced. During stimulus compounding tests, the tone-plus-odor compound occasioned more than double the responses occasioned by either the tone or odor presented individually. Thus, the current study (1) established stimulus control with an ambient olfactory discriminative stimulus in a traditional free-operant setting and (2) extended the generality of stimulus-compounding effects by demonstrating additive summation when olfactory and auditory discriminative stimuli were presented simultaneously.
Collapse
Affiliation(s)
- Scott I Cohn
- Department of Psychology, American University, Washington, DC 20016, USA
| | | |
Collapse
|
47
|
Bradberry CW. Cocaine sensitization and dopamine mediation of cue effects in rodents, monkeys, and humans: areas of agreement, disagreement, and implications for addiction. Psychopharmacology (Berl) 2007; 191:705-17. [PMID: 17031707 DOI: 10.1007/s00213-006-0561-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 08/10/2006] [Indexed: 11/24/2022]
Abstract
BACKGROUND Sensitization of mesocorticolimbic dopamine projections has been a valuable model of neurobiological adaptation to chronic exposure to cocaine and other psychostimulants. DISCUSSIONS In addition to providing an explanation of exaggerated responses to drugs that might explain their increased ability to serve as reinforcers, sensitization has also been incorporated into influential theories of how drug associated cues can acquire increased salience and incentive motivation. However, almost all of the work exploring behavioral and neurochemical sensitization has been conducted in rodents. Importantly, the relatively small amount of work conducted in human and nonhuman primates differs from the rodent work in some important regards. This review will examine areas of convergence and divergence between the rodent and primate literature on sensitization and the ability of drug associated environmental cues to elicit dopamine release. The implications of this comparison for expanding addiction research beyond dopaminergic mechanisms in the striatum/nucleus accumbens will be considered.
Collapse
Affiliation(s)
- Charles W Bradberry
- Department of Psychiatry and Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
48
|
Panlilio LV, Thorndike EB, Schindler CW. Blocking of conditioning to a cocaine-paired stimulus: testing the hypothesis that cocaine perpetually produces a signal of larger-than-expected reward. Pharmacol Biochem Behav 2007; 86:774-7. [PMID: 17445874 PMCID: PMC1986833 DOI: 10.1016/j.pbb.2007.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 03/02/2007] [Accepted: 03/06/2007] [Indexed: 10/23/2022]
Abstract
According to a recent account of addiction, dopaminergic effects of drugs like cocaine mimic the neuronal signal that occurs when a natural reward has a larger value than expected. Consequently, the drug's expected reward value increases with each administration, leading to an over-selection of drug-seeking behavior. One prediction of this hypothesis is that the blocking effect, a cornerstone of contemporary learning theory, should not occur with drug reinforcers. To test this prediction, two groups of rats were trained to self-administer cocaine with a nose-poking response. For 5 sessions, a tone was paired with each self-administered injection (blocking group), or no stimulus was paired with injection (non-blocking group). Then, in both groups, the tone and a light were both paired with each injection for 5 sessions. In subsequent testing, the light functioned as a conditioned reinforcer for a new response (lever-pressing) in the non-blocking group, but not the blocking group. Thus, contrary to prediction, pre-training with the tone blocked conditioning to the light. Although these results fail to support a potentially powerful explanation of addiction, they are consistent with the fact that most conditioning and learning phenomena that occur with non-drug reinforcers can also be demonstrated with drug reinforcers.
Collapse
Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, MD 21224, USA.
| | | | | |
Collapse
|
49
|
Haile CN, Kosten TR, Kosten TA. Genetics of dopamine and its contribution to cocaine addiction. Behav Genet 2006; 37:119-45. [PMID: 17063402 DOI: 10.1007/s10519-006-9115-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Accepted: 09/07/2006] [Indexed: 12/30/2022]
Abstract
Cocaine addiction is a major health and social problem for which there are presently no effective pharmacotherapies. Many of the most promising medications target dopamine based on the large literature that supports its role in addiction. Recent studies show that genetic factors are also important. Rodent models and gene knock-out technology have helped elucidate the involvement of specific genes in the function of the dopamine reward system and intracellular cascades that lead to neuronal changes in this system. Human epidemiological, linkage, and association studies have identified allelic variants (polymorphisms) that give rise to altered metabolism of dopamine and its functional consequences. Individuals with these polymorphisms respond differently to psychostimulants and possibly to pharmacotherapies. Here we review the literature on genetic variations that affect dopamine neurotransmission, responses to psychostimulants and potential treatments for cocaine addiction. Behavioral responses to psychostimulants in animals with different or modified genetics in dopamine signaling are discussed. We also review polymorphisms in humans that affect dopaminergic neurotransmission and alter the subjective effects of psychostimulants. Pharmacotherapies may have increased efficacy when targeted to individuals possessing specific genetic polymophisms in dopamine's metabolic and intracellular messenger systems.
Collapse
Affiliation(s)
- Colin N Haile
- Michael E. DeBakey VA Medical Center, and Meninger Department of Psychiatry, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | |
Collapse
|
50
|
Panlilio LV, Thorndike EB, Schindler CW. Cocaine self-administration under variable-dose schedules in squirrel monkeys. Pharmacol Biochem Behav 2006; 84:235-43. [PMID: 16814853 DOI: 10.1016/j.pbb.2006.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 05/01/2006] [Accepted: 05/05/2006] [Indexed: 11/16/2022]
Abstract
Squirrel monkeys self-administered cocaine under a variable-dose schedule, with the dose varied from injection to injection. As in earlier studies with rats, post-injection pauses varied as a monotonic function of dose, allowing a cocaine dose-effect curve to be obtained during each session. These curves were shifted by pretreatment with dopamine antagonists, demonstrating that this procedure may provide an efficient means of evaluating treatments that affect drug self-administration. However, drug intake eventually became "dysregulated" after extensive training (100-300 sessions), with relatively short pauses following all doses. Dose-sensitivity was restored by adding a 60-s timeout period after each injection, suggesting that dysregulation occurred because the monkeys developed a tendency to self-administer another injection before the previous injection had been adequately distributed. Finally, when the response requirement under the variable-dose schedule was increased from 1 to 10, both the post-injection pause and the rate of responding following the pause ("run rates") were found to vary with dose. The dose-dependency of run rates suggests that post-injection pauses reflect not only motivational factors, such as satiety, but also the direct effects of cocaine on leverpressing.
Collapse
Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
| | | | | |
Collapse
|