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Smith TT, Rupprecht LE, Sved AF, Donny EC. Characterizing the relationship between increases in the cost of nicotine and decreases in nicotine content in adult male rats: implications for tobacco regulation. Psychopharmacology (Berl) 2016; 233:3953-3964. [PMID: 27627909 PMCID: PMC5812478 DOI: 10.1007/s00213-016-4426-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 08/31/2016] [Indexed: 12/29/2022]
Abstract
BACKGROUND A large reduction in the nicotine content of cigarettes may benefit public health by reducing the rate and the prevalence of smoking. A behavioral economics framework suggests that a decrease in nicotine content may be considered an increase in the unit price of nicotine (unit price = reinforcer cost/reinforcer magnitude). Increasing the price of cigarettes (i.e., increasing reinforcer cost) would be considered an equivalent change in unit price to reducing nicotine content (i.e., reducing reinforcer magnitude). OBJECTIVES The goal of the present experiments was to characterize the relationship between increases in nicotine cost and decreases in nicotine dose. MATERIALS AND METHODS A rat self-administration model was used to assess this relationship across three experiments, with an emphasis on very low nicotine doses to model a potential nicotine reduction policy. Cost was manipulated via changes in the number of responses required to earn an infusion. RESULTS Results show that increases in the cost of nicotine and decreases in nicotine content were not equivalent manipulations. Nicotine consumption was more sensitive to nicotine dose than to nicotine cost. Nicotine consumption was also not equivalent across a variety of cost and dose combinations forming a single unit price. CONCLUSIONS Results of the present studies suggest that nicotine reduction is likely to have a large impact on nicotine exposure from cigarettes.
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Affiliation(s)
- Tracy T Smith
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA.
| | - Laura E Rupprecht
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA, 15260, USA
| | - Alan F Sved
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA, 15260, USA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
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Moeller SJ, Stoops WW. Cocaine choice procedures in animals, humans, and treatment-seekers: Can we bridge the divide? Pharmacol Biochem Behav 2015; 138:133-41. [PMID: 26432174 DOI: 10.1016/j.pbb.2015.09.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/22/2015] [Accepted: 09/27/2015] [Indexed: 10/23/2022]
Abstract
Individuals with cocaine use disorder chronically self-administer cocaine to the detriment of other rewarding activities, a phenomenon best modeled in laboratory drug-choice procedures. These procedures can evaluate the reinforcing effects of drugs versus comparably valuable alternatives under multiple behavioral arrangements and schedules of reinforcement. However, assessing drug-choice in treatment-seeking or abstaining humans poses unique challenges: for ethical reasons, these populations typically cannot receive active drugs during research studies. Researchers have thus needed to rely on alternative approaches that approximate drug-choice behavior or assess more general forms of decision-making, but whether these alternatives have relevance to real-world drug-taking that can inform clinical trials is not well-understood. In this mini-review, we (A) summarize several important modulatory variables that influence cocaine choice in nonhuman animals and non-treatment seeking humans; (B) discuss some of the ethical considerations that could arise if treatment-seekers are enrolled in drug-choice studies; (C) consider the efficacy of alternative procedures, including non-drug-related decision-making and 'simulated' drug-choice (a choice is made, but no drug is administered) to approximate drug choice; and (D) suggest opportunities for new translational work to bridge the current divide between preclinical and clinical research.
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Affiliation(s)
- Scott J Moeller
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, United States; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
| | - William W Stoops
- Department of Behavioral Science and Center on Drug and Alcohol Research, University of Kentucky College of Medicine, Lexington, KY, United States; Department of Psychiatry, University of Kentucky College of Medicine, Lexington, KY, United States; Department of Psychology, University of Kentucky College of Arts and Sciences, Lexington, KY, United States.
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Interaction between behavioral and pharmacological treatment strategies to decrease cocaine choice in rhesus monkeys. Neuropsychopharmacology 2013; 38:395-404. [PMID: 22968813 PMCID: PMC3547190 DOI: 10.1038/npp.2012.193] [Citation(s) in RCA: 25] [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
Behavioral and pharmacotherapeutic approaches constitute two prominent strategies for treating cocaine dependence. This study investigated interactions between behavioral and pharmacological strategies in a preclinical model of cocaine vs food choice. Six rhesus monkeys, implanted with a chronic indwelling double-lumen venous catheter, initially responded under a concurrent schedule of food delivery (1-g pellets, fixed-ratio (FR) 100 schedule) and cocaine injections (0-0.1 mg/kg/injection, FR 10 schedule) during continuous 7-day treatment periods with saline or the agonist medication phenmetrazine (0.032-0.1 mg/kg/h). Subsequently, the FR response requirement for cocaine or food was varied (food, FR 100; cocaine, FR 1-100; cocaine, FR 10; food, FR 10-300), and effects of phenmetrazine on cocaine vs food choice were redetermined. Decreases in the cocaine FR or increases in the food FR resulted in leftward shifts in the cocaine choice dose-effect curve, whereas increases in the cocaine FR or decreases in the food FR resulted in rightward shifts in the cocaine choice dose-effect curve. The efficacy of phenmetrazine to decrease cocaine choice varied systematically as a function of the prevailing response requirements, such that phenmetrazine efficacy was greatest when cocaine choice was maintained by relatively low unit cocaine doses. These results suggest that efficacy of pharmacotherapies to modulate cocaine use can be influenced by behavioral contingencies of cocaine availability. Agonist medications may be most effective under contingencies that engender choice of relatively low cocaine doses.
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Preclinical Determinants of Drug Choice under Concurrent Schedules of Drug Self-Administration. Adv Pharmacol Sci 2012; 2012:281768. [PMID: 23243420 PMCID: PMC3515886 DOI: 10.1155/2012/281768] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 10/14/2012] [Indexed: 12/20/2022] Open
Abstract
Drug self-administration procedures have played a critical role in the experimental analysis of psychoactive compounds, such as cocaine, for over 50 years. While there are numerous permutations of this procedure, this paper will specifically focus on choice procedures using concurrent schedules of intravenous drug self-administration. The aims of this paper are to first highlight the evolution of drug choice procedures and then review the subsequent preclinical body of literature utilizing these choice procedures to understand the environmental, pharmacological, and biological determinants of the reinforcing stimulus effects of drugs. A main rationale for this paper is our proposition that choice schedules are underutilized in investigating the reinforcing effects of drugs in assays of drug self-administration. Moreover, we will conclude with potential future directions and unexplored scientific space for the use of drug choice procedures.
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Oleson EB, Richardson JM, Roberts DCS. A novel IV cocaine self-administration procedure in rats: differential effects of dopamine, serotonin, and GABA drug pre-treatments on cocaine consumption and maximal price paid. Psychopharmacology (Berl) 2011; 214:567-77. [PMID: 21110008 PMCID: PMC3289955 DOI: 10.1007/s00213-010-2058-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 10/14/2010] [Indexed: 11/26/2022]
Abstract
RATIONALE Behavior occurring during cocaine self-administration can be classified as either consummatory or appetitive. These two concepts are usually addressed independently using separate reinforcement schedules. For example, appetitive behavior can be assessed with a progressive ratio schedule, whereas consummatory behavior is typically measured using a fixed ratio schedule. OBJECTIVES Depending on the schedule used, it is often difficult to determine whether a particular drug pretreatment is affecting self-administration through an effect on appetitive responding, consummatory responding, or perhaps both. In the present study, we tested the effect of pretreating rats with four different drugs on appetitive and consummatory behaviors. MATERIALS AND METHODS We recently developed a technique that provides an independent assessment of both behavioral concepts within the same experimental session. In this threshold procedure, rats are offered a descending series of 11 unit doses (422-1.3 μg/injection) during consecutive timed intervals under a fixed-ratio schedule. Consummatory behavior can be analyzed by assessing intake at high unit doses; an estimate of appetitive responding can be determined from responding occurring at the threshold dose. Applying behavioral economics to these data provides dependent measures of consumption when minimally constrained by price and the maximal price paid (P (max)) for cocaine. RESULTS Haloperidol increased cocaine consumption when minimally constrained by price but decreased P (max). In contrast, D: -amphetamine increased P (max). Fluoxetine decreased P (max) and consumption when minimally constrained by price. Baclofen selectively decreased P (max). CONCLUSIONS These data suggest that drug pretreatments can alter consummatory and appetitive behavior differently because each concept involves distinct neural mechanisms.
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Affiliation(s)
- Erik B Oleson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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Root DH, Fabbricatore AT, Barker DJ, Ma S, Pawlak AP, West MO. Evidence for habitual and goal-directed behavior following devaluation of cocaine: a multifaceted interpretation of relapse. PLoS One 2009; 4:e7170. [PMID: 19779607 PMCID: PMC2744871 DOI: 10.1371/journal.pone.0007170] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 08/20/2009] [Indexed: 11/19/2022] Open
Abstract
Background Cocaine addiction is characterized as a chronically relapsing disorder. It is believed that cues present during self-administration become learned and increase the probability that relapse will occur when they are confronted during abstinence. However, the way in which relapse-inducing cues are interpreted by the user has remained elusive. Recent theories of addiction posit that relapse-inducing cues cause relapse habitually or automatically, bypassing processing information related to the consequences of relapse. Alternatively, other theories hypothesize that relapse-inducing cues produce an expectation of the drug's consequences, designated as goal-directed relapse. Discrete discriminative stimuli signaling the availability of cocaine produce robust cue-induced responding after thirty days of abstinence. However, it is not known whether cue-induced responding is a goal-directed action or habit. Methodology/Principal Findings We tested whether cue-induced responding is a goal-directed action or habit by explicitly pairing or unpairing cocaine with LiCl-induced sickness (n = 7/group), thereby decreasing or not altering the value of cocaine, respectively. Following thirty days of abstinence, no difference in responding between groups was found when animals were reintroduced to the self-administration environment alone, indicating habitual behavior. However, upon discriminative stimulus presentations, cocaine-sickness paired animals exhibited decreased cue-induced responding relative to unpaired controls, indicating goal-directed behavior. In spite of the difference between groups revealed during abstinent testing, no differences were found between groups when animals were under the influence of cocaine. Conclusions/Significance Unexpectedly, both habitual and goal-directed responding occurred during abstinent testing. Furthermore, habitual or goal-directed responding may have been induced by cues that differed in their correlation with the cocaine infusion. Non-discriminative stimulus cues were weak correlates of the infusion, which failed to evoke a representation of the value of cocaine and led to habitual behavior. However, the discriminative stimulus–nearly perfectly correlated with the infusion–likely evoked a representation of the value of the infusion and led to goal-directed behavior. These data indicate that abstinent cue-induced responding is multifaceted, dynamically engendering habitual or goal-directed behavior. Moreover, since goal-directed behavior terminated habitual behavior during testing, therapeutic approaches aimed at reducing the perceived value of cocaine in addicted individuals may reduce the capacity of cues to induce relapse.
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Affiliation(s)
- David H. Root
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Anthony T. Fabbricatore
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - David J. Barker
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Sisi Ma
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Anthony P. Pawlak
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Mark O. West
- Department of Psychology, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
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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.
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LeSage MG, Stafford D, Glowa JR. Preclinical research on cocaine self-administration: environmental determinants and their interaction with pharmacological treatment. Neurosci Biobehav Rev 1999; 23:717-41. [PMID: 10392662 DOI: 10.1016/s0149-7634(99)00015-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It has been asserted that any comprehensive understanding of cocaine abuse and its treatment will require attention to both behavioral and pharmacological variables. Although the preclinical literature evaluating the effects of pharmacological variables on cocaine self-administration has been extensively reviewed, no comprehensive review of the effects of environmental variables on cocaine self-administration has been published. The present review summarizes and critiques the preclinical findings on environmental determinants of cocaine self-administration. The influence of environmental variables on the effects of pharmacological interventions on cocaine self-administration are also described. Several environmental variables have been shown to affect cocaine self-administration, including unit dose, schedule of cocaine delivery, schedules of nondrug stimuli, behavioral history, conditioned stimuli, food deprivation, exposure to stress, and rearing environment. Among these variables, unit dose, schedule of cocaine delivery, availability of alternative nondrug reinforcers, food deprivation, and rearing environment have also been shown to alter pharmacological treatment effects on cocaine self-administration. Thus, drug effects on cocaine self-administration are malleable and dependent upon the environmental context within which they occur. Suggestions for future research on the effects of these and other environmental variables on cocaine self-administration and its pharmacological treatment are presented.
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Affiliation(s)
- M G LeSage
- Department of Pharmacology and Therapeutics, Louisiana State University Medical Center at Shreveport, 71130-3932, USA
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