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Garcia-Rivas V, Fiancette JF, Tostain J, de Maio G, Ceau M, Wiart JF, Gaulier JM, Deroche-Gamonet V. Individual variations in motives for nicotine self-administration in male rats: evidence in support for a precision psychopharmacology. Transl Psychiatry 2024; 14:85. [PMID: 38336930 PMCID: PMC10858238 DOI: 10.1038/s41398-024-02774-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/07/2024] [Accepted: 01/10/2024] [Indexed: 02/12/2024] Open
Abstract
The significant heterogeneity in smoking behavior among smokers, coupled with the inconsistent efficacy of approved smoking cessation therapies, supports the presence of individual variations in the mechanisms underlying smoking. This emphasizes the need to shift from standardized to personalized smoking cessation therapies. However, informed precision medicine demands precision fundamental research. Tobacco smoking is influenced and sustained by diverse psychopharmacological interactions between nicotine and environmental stimuli. In the classical experimental rodent model for studying tobacco dependence, namely intravenous self-administration of nicotine, seeking behavior is reinforced by the combined delivery of nicotine and a discrete cue (nicotine+cue). Whether self-administration behavior is driven by the same psychopharmacological mechanisms across individual rats remains unknown and unexplored. To address this, we employed behavioral pharmacology and unbiased cluster analysis to investigate individual differences in the mechanisms supporting classical intravenous nicotine self-administration (0.04 mg/kg/infusion) in male outbred Sprague-Dawley rats. Our analysis identified two clusters: one subset of rats sought nicotine primarily for its reinforcing effects, while the second subset sought nicotine to enhance the reinforcing effects of the discrete cue. Varenicline (1 mg/kg i.p.) reduced seeking behavior in the former group, whereas it tended to increase in the latter group. Crucially, despite this fundamental qualitative difference revealed by behavioral manipulation, the two clusters exhibited quantitatively identical nicotine+cue self-administration behavior. The traditional application of rodent models to study the reinforcing and addictive effects of nicotine may mask individual variability in the underlying motivational mechanisms. Accounting for this variability could significantly enhance the predictive validity of translational research.
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Affiliation(s)
- Vernon Garcia-Rivas
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France.
- INSERM, Magendie, U1215, F-33000, Bordeaux, France.
- Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA.
| | - Jean-François Fiancette
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France
- INSERM, Magendie, U1215, F-33000, Bordeaux, France
| | - Jessica Tostain
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France
- INSERM, Magendie, U1215, F-33000, Bordeaux, France
| | - Giulia de Maio
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France
- INSERM, Magendie, U1215, F-33000, Bordeaux, France
| | - Matias Ceau
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France
- INSERM, Magendie, U1215, F-33000, Bordeaux, France
| | | | - Jean-Michel Gaulier
- CHU Lille, Unité Fonctionnelle de Toxicologie, F-59037, Lille, France
- Univ. Lille, ULR 4483, IMPECS - IMPact de l'Environnement Chimique sur la Santé humaine, F-59045, Lille, France
| | - Véronique Deroche-Gamonet
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33000, Bordeaux, France.
- INSERM, Magendie, U1215, F-33000, Bordeaux, France.
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Smethells JR, Burroughs D, Saykao A, LeSage MG. The relative reinforcing efficacy of nicotine in an adolescent rat model of attention-deficit hyperactivity disorder. Front Psychiatry 2023; 14:1154773. [PMID: 37255676 PMCID: PMC10225533 DOI: 10.3389/fpsyt.2023.1154773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/14/2023] [Indexed: 06/01/2023] Open
Abstract
Introduction Attention-deficit/hyperactivity disorder (ADHD) is an independent risk factor for tobacco use disorder. Individuals with ADHD are more likely to begin smoking at a younger age, become a daily smoker sooner, smoke more cigarettes per day, and exhibit greater nicotine dependence than individuals without ADHD. It is unclear whether these findings are due to the reinforcing efficacy of nicotine per se being greater among individuals with ADHD. The purpose of the present study was to examine this issue using an animal model of ADHD, the spontaneously hypertensive rat (SHR) strain. Methods Adolescent SHR and Wistar (control) rats were given access to a typically reinforcing nicotine unit dose (30 μg/kg), a threshold reinforcing nicotine dose (4 μg/kg), or saline under an FR 1 (week 1) and FR 2 (week 2) schedule during 23 h sessions to examine acquisition of self-administration. Behavioral economic demand elasticity was then evaluated at the 30 μg/kg dose through an FR escalation procedure. Results At the 30 μg/kg dose, SHR rats exhibited a lower average response rate, lower mean active to inactive lever discrimination ratio, and lower proportion of rats acquiring self-administration compared to control rats. During demand assessment, SHR rats showed no significant difference from Wistars in demand intensity (Q0) or elasticity (α; i.e., reinforcing efficacy). In addition, no strain difference in acquisition measures were observed at the 4 μg/kg dose. Discussion These findings suggest that the increased risk of tobacco use disorder in adolescents with ADHD may not be attributable to a greater reinforcing efficacy of nicotine, and that other aspects of tobacco smoking (e.g., non-nicotine constituents, sensory factors) may play a more important role. A policy implication of these findings is that a nicotine standard to reduce initiation of tobacco use among adolescents in the general population may also be effective among those with ADHD.
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Affiliation(s)
- John R. Smethells
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States
| | | | - Amy Saykao
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States
| | - Mark G. LeSage
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
- Department of Psychology, University of Minnesota, Minneapolis, MN, United States
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LeSage MG. Stimulus functions of nicotine. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 93:133-170. [PMID: 35341565 PMCID: PMC9438898 DOI: 10.1016/bs.apha.2021.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Behavioral pharmacology has made vital contributions to the concepts and methods used in tobacco and other drug use research, and is largely responsible for the now generally accepted notion that nicotine is the primary component in tobacco that engenders and maintains tobacco use. One of the most important contributions of behavioral pharmacology to the science of drug use is the notion that drugs can act as environmental stimuli that control behavior in many of the same ways as other stimuli (e.g., visual, gustatory, olfactory). The purpose of this chapter is to provide an overview of research that illustrates the respondent and operant stimulus functions of nicotine, using a contemporary taxonomy of stimulus functions as a general framework. Each function is formally defined and examples from research on the behavioral pharmacology of nicotine are presented. Some of the factors that modulate each function are also discussed. The role of nicotine's stimulus functions in operant and respondent theories of tobacco use is examined and some suggestions for future research are presented. The chapter illustrates how a taxonomy of stimulus functions can guide conceptions of tobacco use and direct research and theory accordingly.
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Schlagintweit HE, Tyndale RF, Hendershot CS. Acute effects of a very low nicotine content cigarette on laboratory smoking lapse: Impacts of nicotine metabolism and nicotine dependence. Addict Biol 2021; 26:e12930. [PMID: 32573054 DOI: 10.1111/adb.12930] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/29/2020] [Accepted: 05/31/2020] [Indexed: 12/13/2022]
Abstract
Reducing cigarette nicotine content to nonaddictive levels facilitates smoking cessation; however, very low nicotine content cigarettes (VLNCs) may not be equally effective across heterogeneous smokers. We evaluated the impact of acute VLNC smoking versus control (sham puffs) on craving, withdrawal and smoking lapse behaviour and whether genetically influenced differences in nicotine metabolism and individual differences in nicotine dependence moderate observed effects. Thirty-three overnight-abstinent smokers (15 slow vs. 17 normal nicotine metabolizers; 17 low vs. 16 high nicotine dependence) smoked a 0.05-mg nicotine VLNC during one session and took sham VLNC puffs during another session, in a counterbalanced order. Craving and withdrawal were assessed before and after smoking and sham puffing. Next, participants completed the McKee Smoking Lapse Task, which measures ability to resist smoking and quantity of ad libitum smoking. VLNC (vs. sham) reduced craving and withdrawal, increased ability to resist smoking and reduced ad libitum smoking. VLNC-induced reduction in craving for positive reinforcement was greater in slow (vs. normal) metabolizers. Nicotine metabolism did not moderate any other VLNC responses. High-dependence (vs. low-dependence) participants engaged in greater ad lib smoking across VLNC and sham conditions. Nicotine dependence did not moderate VLNC responses. VLNC reduced craving, withdrawal and smoking lapse behaviour. Individual differences in nicotine metabolism and dependence had a minimal impact on VLNC responses; however, VLNCs were less effective at reducing craving for positive reinforcement among normal (vs. slow) metabolizers. These findings suggest that desirable VLNC effects may extend across heterogeneous groups of smokers.
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Affiliation(s)
- Hera E. Schlagintweit
- Campbell Family Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
| | - Rachel F. Tyndale
- Campbell Family Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
| | - Christian S. Hendershot
- Campbell Family Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Institute for Mental Health Policy Research Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychology University of Toronto Toronto Ontario Canada
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Smethells JR, Burroughs D, Saykao A, Pentel PR, Rezvani AH, LeSage MG. The reinforcement threshold and elasticity of demand for nicotine in an adolescent rat model of depression. Drug Alcohol Depend 2021; 219:108433. [PMID: 33310485 PMCID: PMC7855441 DOI: 10.1016/j.drugalcdep.2020.108433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 11/15/2022]
Abstract
BACKGROUND The Food and Drug Administration (FDA) is considering setting a nicotine standard for tobacco products to reduce their addictiveness. Such a standard should account for the apparent greater vulnerability to nicotine addiction in some subpopulations, such as adolescents with depression. The present study examined whether the reinforcement threshold and elasticity of demand (i.e., reinforcing efficacy) for nicotine in a genetic inbred rat model of depression (Flinders Sensitive Line [FSL]) differs from an outbred control strain. METHODS Acquisition of nicotine self-administration (NSA) across a wide range of nicotine doses was measured in both FSL and Sprague-Dawley (SD) control adolescent rats. At the highest dose, elasticity of demand was also measured. Nicotine pharmacokinetics was examined to determine whether it might modulate NSA, as it does smoking in humans. RESULTS FSL rats acquired self-administration quicker and showed more inelastic demand (greater reinforcing efficacy) than SDs at the highest unit dose. However, there was no strain difference in the reinforcement threshold of nicotine. FSL rats exhibited faster nicotine clearance, larger volume of distribution, and lower plasma and brain nicotine concentrations. However, these differences were not consistently related to strain differences in NSA measures. CONCLUSION These findings are consistent with studies showing greater dependence and reinforcing efficacy of cigarettes in smokers with depression and those with relatively fast nicotine metabolism. However, these findings also suggest that a nicotine standard to reduce initiation of tobacco use should be similarly effective in both the general adolescent population and those with depression.
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Affiliation(s)
- John R. Smethells
- Hennepin Healthcare Research Institute, Minneapolis, MN,Departments of Medicine and Pharmacology, University of Minnesota Medical School, Minneapolis, MN
| | | | - Amy Saykao
- Hennepin Healthcare Research Institute, Minneapolis, MN
| | - Paul R. Pentel
- Hennepin Healthcare Research Institute, Minneapolis, MN,Departments of Medicine and Pharmacology, University of Minnesota Medical School, Minneapolis, MN
| | - Amir H. Rezvani
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC
| | - Mark G. LeSage
- Hennepin Healthcare Research Institute, Minneapolis, MN,Departments of Medicine and Pharmacology, University of Minnesota Medical School, Minneapolis, MN,Department of Psychology, University of Minnesota, Minneapolis, MN
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Nicotine reduction does not alter essential value of nicotine or reduce cue-induced reinstatement of nicotine seeking. Drug Alcohol Depend 2020; 212:108020. [PMID: 32362438 PMCID: PMC7293915 DOI: 10.1016/j.drugalcdep.2020.108020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 03/09/2020] [Accepted: 04/13/2020] [Indexed: 01/10/2023]
Abstract
Reduction of nicotine content in tobacco products is a regulatory control strategy intended to decrease smoking dependence, and is hypothesized to produce gradual reductions of nicotine intake. Rats were initially trained to self-administer 0.06 mg/kg/infusion nicotine (Phase 1), which was followed by a threshold procedure to determine nicotine demand via a behavioral economics (BE) paradigm (Phase 2). Rats then either self-administered the training dose (high dose group), or were switched to a low dose of nicotine (0.001 mg/kg/infusion; low dose group) in Phase 3. Both groups then underwent a second threshold procedure and demand curves were re-determined (Phase 4). In Phase 5, responding for nicotine was extinguished over the course of 21 sessions. Cue-induced reinstatement was then evaluated (Phase 6). Rats in the low dose group maintained a steady amount of infusions, and thus, did not compensate for nicotine reduction. Rats in the low dose group also showed similar demand elasticity and nicotine seeking (Phase 6) compared to the high dose group, indicating that nicotine reduction did not decrease nicotine demand or seeking. Further, both groups displayed resistance to extinction, indicating that nicotine reduction did not facilitate extinction learning. These results suggest that although compensation of intake does not occur, decreasing the dose of nicotine does not alter nicotine reinforcement value or relapse vulnerability. Further, these results indicate persistence of nicotine-motivated behavior after self-administration of a low nicotine dose. Translationally, these results suggest that alternative strategies may be needed to achieve positive smoking cessation outcomes.
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Perkins KA, Karelitz JL. Differences in acute reinforcement across reduced nicotine content cigarettes. Psychopharmacology (Berl) 2020; 237:1885-1891. [PMID: 32221696 PMCID: PMC7244375 DOI: 10.1007/s00213-020-05509-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/10/2020] [Indexed: 11/28/2022]
Abstract
RATIONALE The smallest difference in nicotine that can change a smoker's cigarette preference is not clearly known. OBJECTIVE A procedure to efficiently identify the difference in nicotine needed to change cigarette preference could help inform research to gauge effects of a nicotine reduction policy. METHODS Using a within-subject design, we assessed preference for research cigarettes varying in nicotine contents (NIC; 18.7, 10.8, 5.3, 2.3, and 1.3 mg/g of tobacco), relative to a very low nicotine cigarette (VLNC; 0.4 mg/g), in 17 adult-dependent non-menthol smokers abstinent overnight. Only one NIC was compared vs. the VLNC per session, with order of the five NIC contents randomized across sessions on five separate days. Preference for each NIC vs. VLNC was determined by validated forced choice procedure, with those NIC chosen more than VLNC indicating greater reinforcement due to greater nicotine per se. Secondarily, less preference for lower NIC (vs. VLNC), relative to choice for the highest NIC, 18.7 mg/g (vs. VLNC), indexed reduced reinforcement. RESULTS Overall, NIC choices increased as their nicotine increased, as anticipated. Relative to the 0.4 mg/g VLNC, choice was greater for NIC ≥ 5.3 mg/g but not ≤ 2.3 mg/g. Correspondingly, relative to choice for 18.7 mg/g, choice was less for NIC ≤ 2.3 mg/g but not ≥ 5.3 mg/g. CONCLUSIONS Although replication with larger samples and longer access is needed, results indicate that nicotine reduction to ≤ 2.3 mg/g in cigarettes would attenuate reinforcement. This choice procedure may efficiently inform future clinical trials to assess relative reinforcing effects of smoking reduced nicotine cigarettes.
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Affiliation(s)
- Kenneth A Perkins
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA.
| | - Joshua L Karelitz
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
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Berman ML, Glasser AM. Nicotine Reduction in Cigarettes: Literature Review and Gap Analysis. Nicotine Tob Res 2020; 21:S133-S144. [PMID: 31867659 PMCID: PMC6939782 DOI: 10.1093/ntr/ntz162] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/28/2019] [Indexed: 11/13/2022]
Abstract
BACKGROUND The US Food and Drug Administration (FDA) is considering reducing nicotine levels in cigarettes to "minimally or non-addictive levels." However, important research gaps remain, and the FDA must determine when the available research is sufficient to support moving forward. METHODS The authors conducted a systematic review of research articles in PubMed relating to nicotine reduction. Building on a review of risk assessment best practices, the authors also developed a risk assessment framework for tobacco regulation and used it to guide a gap analysis of nicotine reduction research. RESULTS The final sample consisted of 78 articles. The majority examined either nicotine dependence on very low nicotine cigarettes (VLNCs) or markers of potential health effects of using VLNCs. One-third of the identified articles reported results from four large randomized controlled trials (RCTs). While these studies report promising results and suggest that a nicotine reduction rule would be a powerful tool to reduce cigarette smoking, our gap analysis suggests that there is a need for studies that better reflect the use and availability of a wide range of tobacco/nicotine products and the potential for dual- or multi-product use. CONCLUSION The current body of research on nicotine reduction is weighted towards RCTs, which is appropriate for a policy that has not yet been implemented anywhere in the world. The FDA must consider a wide range of factors that may impact a product standard's public health impact, including those difficult to assess in RCTs, such as a nicotine reduction rule's impact on smoking initiation and relapse. IMPLICATIONS This systematic review presents a gap analysis based on a risk assessment framework to help identify remaining research priorities to inform FDA's potential product standard to reduce nicotine levels in cigarettes. Quickly addressing those gaps would support the FDA's effort to develop a nicotine reduction product standard that will be effective and withstand legal challenges.
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Affiliation(s)
- Micah L Berman
- College of Public Health, Ohio State University, Columbus, OH.,Moritz College of Law, Ohio State University, Columbus, OH
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Smith TT, Koopmeiners JS, Hatsukami DK, Tessier KM, Benowitz NL, Murphy SE, Strasser AA, Tidey JW, Blount BC, Valentin L, Bravo Cardenas R, Watson C, Pirkle JL, Donny EC. Mouth-Level Nicotine Intake Estimates from Discarded Filter Butts to Examine Compensatory Smoking in Low Nicotine Cigarettes. Cancer Epidemiol Biomarkers Prev 2020; 29:643-649. [PMID: 32102909 PMCID: PMC7100998 DOI: 10.1158/1055-9965.epi-19-0905] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/15/2019] [Accepted: 12/09/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND A mandated reduction in the nicotine content of cigarettes could reduce smoking rate and prevalence. However, one concern is that smokers may compensate by increasing the intensity with which they smoke each cigarette to obtain more nicotine. This study assessed whether smokers engage in compensatory smoking by estimating the mouth-level nicotine intake of low nicotine cigarettes smoked during a clinical trial. METHODS Smokers were randomly assigned to receive cigarettes with one of five nicotine contents for 6 weeks. An additional group received a cigarette with the lowest nicotine content, but an increased tar yield. The obtained mouth-level nicotine intake from discarded cigarette butts for a subset of participants (51-70/group) was estimated using solanesol as described previously. A compensation index was calculated for each group to estimate the proportion of nicotine per cigarette recovered through changes in smoking intensity. RESULTS There was no significant increase in smoking intensity for any of the reduced nicotine cigarettes as measured by the compensation index (an estimated 0.4% of the nicotine lost was recovered in the lowest nicotine group; 95% confidence interval, -0.1 to 1.2). There was a significant decrease in smoking intensity for very low nicotine content cigarettes with increased tar yield. CONCLUSIONS Reductions in nicotine content did not result in compensatory changes in how intensively participants smoked research cigarettes. IMPACT Combined with data from clinical trials showing a reduction in cigarettes smoked per day, these data suggest that a reduction in nicotine content is unlikely to result in increased smoke exposure.
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Affiliation(s)
- Tracy T Smith
- Department of Psychiatry and Behavioral Sciences, and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina.
| | - Joseph S Koopmeiners
- Division of Biostatistics, School of Public Health, and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Dorothy K Hatsukami
- Department of Psychiatry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Katelyn M Tessier
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Neal L Benowitz
- Departments of Medicine and Bioengineering & Therapeutic Sciences, University of California, San Francisco, San Francisco, California
| | - Sharon E Murphy
- Department of Biochemistry Molecular Biology and BioPhysics and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Andrew A Strasser
- Department of Psychiatry, Perelman School of Medicine, and Abraham Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jennifer W Tidey
- Department of Behavioral and Social Sciences, Brown University, Providence, Rhode Island
| | - Benjamin C Blount
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Liza Valentin
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Roberto Bravo Cardenas
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Clifford Watson
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - James L Pirkle
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Eric C Donny
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
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Comparison of the Relative Abuse Liability of Electronic Cigarette Aerosol Extracts and Nicotine Alone in Adolescent Rats: A Behavioral Economic Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030860. [PMID: 32019080 PMCID: PMC7037300 DOI: 10.3390/ijerph17030860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 12/02/2022]
Abstract
Background: Characterizing the determinants of the abuse liability of electronic cigarettes (ECs) in adolescents is needed to inform product regulation by the United States Food and Drug Administration (FDA). We recently reported that Vuse Menthol EC aerosol extract containing nicotine and a range of non-nicotine constituents (e.g., menthol, propylene glycol) had reduced aversive effects compared to nicotine alone in adolescent rats, whereas Aroma E-Juice EC aerosol extract did not. The current study used a behavioral economic approach to compare the relative abuse liability of these EC extracts and nicotine alone in an i.v. self-administration (SA) model in adolescents. Methods: Adolescents were tested for the SA of EC extracts prepared using an ethanol (ETOH) solvent or nicotine and saline, with and without 4% ETOH (i.e., the same concentration in the EC extracts) in 23 h/day sessions. Results. Although acquisition of SA was faster for nicotine + ETOH compared to all other formulations, the elasticity of demand for all nicotine-containing formulations was similar. Conclusions: EC aerosol extracts did not have greater abuse liability than nicotine alone in adolescents. These data suggest that nicotine may be the primary determinant of the abuse liability of these ECs in youth, at least in terms of the primary reinforcing effects of ECs mediated within the central nervous system.
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Perkins KA. Research on Behavioral Discrimination of Nicotine May Inform FDA Policy on Setting a Maximum Nicotine Content in Cigarettes. Nicotine Tob Res 2019; 21:S5-S12. [PMID: 31867642 PMCID: PMC6939773 DOI: 10.1093/ntr/ntz136] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/06/2019] [Indexed: 12/13/2022]
Abstract
INTRODUCTION The Food and Drug Administration may set a maximum nicotine content in cigarettes to minimize smoking's addictiveness. Our recent research may indirectly support setting levels applicable to the population of dependent smokers below 1 mg/g (mg nicotine/g of tobacco filler). METHODS Using a within-subjects design in laboratory-based studies totaling 61 nontreatment seeking adult dependent smokers, Spectrum research cigarettes with nicotine contents ranging from 1.3 to 17 mg/g (just one per session) were compared with the lowest content available, 0.4 mg/g. Identified for each participant was the smallest difference in nicotine content, or "threshold," between cigarettes that still supported behavioral discrimination (ie, ability to objectively distinguish their difference). The next lower nicotine content cigarette, not discriminated (by definition), was labeled their "subthreshold." Subjective perceptions and choice behavior were also assessed. RESULTS Thresholds varied widely among all 61 smokers but, importantly, fewer than 7% of smokers could discriminate the two lowest, 1.3 versus 0.4 mg/g nicotine, meaning more than 90% could not do so. Moreover, we found a consistent association between their nicotine discrimination threshold and their subjective perceptions and subsequent reinforcement behavior later in the session. Specifically, a participant's discrimination threshold cigarette was also more highly rated and preferred (ie, self-administered), whereas their subthreshold cigarette was rated similarly to the 0.4 mg/g and not preferred. CONCLUSIONS Cigarette nicotine content below the threshold for perceiving nicotine's effects (ie, its discriminability) in nearly all smokers from a no nicotine comparison is likely below 1.0 mg/g, or less than or equal to 10% of that in typical commercial cigarettes. IMPLICATIONS Cigarettes with nicotine contents able to be discriminated (threshold) are also reinforcing, and those unable to be discriminated are not reinforcing, as anticipated. Yet, research explicitly comparing cigarettes with contents below 1.0 mg/g versus no nicotine (ie, a "placebo") is needed with larger samples. Results may confirm what nicotine content lower than 1.0 mg/g is below the threshold for discrimination (and self-administration) in the vast majority (>95%) of adult dependent smokers as well as teens beginning to smoke. Identifying that content would strongly support the Food and Drug Administration policy to establish a maximum nicotine content in cigarettes that will not maintain dependence.
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Marusich JA, Wiley JL, Silinski MAR, Thomas BF, Meredith SE, Gahl RF, Jackson KJ. Comparison of cigarette, little cigar, and waterpipe tobacco smoke condensate and e-cigarette aerosol condensate in a self-administration model. Behav Brain Res 2019; 372:112061. [PMID: 31254537 PMCID: PMC6664429 DOI: 10.1016/j.bbr.2019.112061] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/15/2022]
Abstract
The pharmacological effects of tobacco products are primarily mediated by nicotine; however, research suggests that several non-nicotine tobacco constituents may alter the reinforcing effects of nicotine. This study evaluated the reinforcing effects of aqueous solutions of smoke/aerosol condensate from cigarettes, little cigars, electronic cigarettes (e-cigarettes), and waterpipe tobacco in a self-administration procedure to determine if abuse liability of these tobacco products differed. Adult male Sprague-Dawley rats (n = 64 total) were trained to self-administer intravenous nicotine (30 μg/kg/infusion) on a fixed ratio 5 schedule of reinforcement. Following nicotine dose-effect assessment (1, 7.5, 15, and 30 μg/kg/infusion), rats were given access to smoke/aerosol condensate derived from their assigned tobacco product. Rats responded for smoke/aerosol condensate containing 1, 7.5, 15, and 30 μg/kg/infusion nicotine, with the ratio of nicotine:non-nicotine constituents held constant across doses for each tobacco product. Responding for nicotine or smoke/aerosol condensate was also assessed on a progressive ratio schedule of reinforcement. Cigarette, little cigar, and e-cigarette smoke/aerosol condensates shifted the nicotine dose-effect curve leftward, whereas waterpipe tobacco smoke condensate shifted the dose-effect curve rightward. Smoke/aerosol condensate from all tobacco products produced similar levels of responding compared to nicotine alone during the progressive ratio phase. Results suggest that non-nicotine constituents in cigarettes, little cigars, and e-cigarettes differentially enhance nicotine's reinforcing potency. In contrast, waterpipe tobacco blunted nicotine's reinforcing potency, suggesting that it may contain unique constituents that dampen nicotine's reinforcing effects.
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Affiliation(s)
- Julie A Marusich
- Center for Drug Discovery, RTI International, 3040 Cornwallis Rd, Research Triangle Park, NC, 27709, USA.
| | - Jenny L Wiley
- Center for Drug Discovery, RTI International, 3040 Cornwallis Rd, Research Triangle Park, NC, 27709, USA
| | - Melanie A R Silinski
- Analytical Sciences, RTI International, 3040 Cornwallis Rd, Research Triangle Park, NC, 27709, USA
| | - Brian F Thomas
- Analytical Chemistry and Pharmaceutics, RTI International, 3040 Cornwallis Rd, Research Triangle Park, NC, 27709, USA
| | - Steven E Meredith
- U.S. Food and Drug Administration, Center for Tobacco Products, 10903 New Hampshire Ave., Silver Spring, MD, 20993, USA
| | - Robert F Gahl
- U.S. Food and Drug Administration, Center for Tobacco Products, 10903 New Hampshire Ave., Silver Spring, MD, 20993, USA
| | - Kia J Jackson
- U.S. Food and Drug Administration, Center for Tobacco Products, 10903 New Hampshire Ave., Silver Spring, MD, 20993, USA
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13
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Holmes NM, Pan J, Davis A, Panayi MC, Clemens KJ. Rats choose high doses of nicotine in order to compensate for changes in its price and availability. Addict Biol 2019; 24:849-859. [PMID: 29920857 DOI: 10.1111/adb.12637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 12/13/2022]
Abstract
Restricting when and where smoking can occur is a major focus of public health policies in Western countries. In conjunction with increased taxation, these approaches have contributed to a reduction in smoking uptake among adolescents, yet the consequences for established smokers are less clear. In order to further explore this relationship, we developed a novel animal model of restricted nicotine self-administration. Rats were trained to choose between three doses of nicotine (15, 30 and 60 μg/kg/infusion) under conditions where nicotine was (1) freely available at a low cost (20-second post-infusion time-out, fixed-ratio 1 [FR1]), (2) available under restricted access at a low cost (300-second post-infusion time-out, FR1), or (3) freely available at a high cost (20-second post-infusion time-out, FR5). We demonstrate that as access to nicotine is restricted or when cost increases, rats compensate for these changes by increasing their intake of the highest dose of nicotine available. This preference was impervious to treatment with the smoking cessation medication varenicline, but was reduced when the cost of the highest dose only was increased, or when nicotine was again made freely available at a low cost. These results provide the first evidence in rats that nicotine availability and cost influence nicotine choice independently of variations in nicotine and context exposure. They imply that established smokers may compensate for changes in the availability and cost of tobacco by increasing their rate of smoking when they are free to do so.
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Affiliation(s)
- Nathan M. Holmes
- School of Psychology University of New South Wales Sydney Australia
| | - Jiajing Pan
- School of Psychology University of New South Wales Sydney Australia
| | - Andrew Davis
- School of Psychology University of New South Wales Sydney Australia
| | - Marios C. Panayi
- School of Psychology University of New South Wales Sydney Australia
| | - Kelly J. Clemens
- School of Psychology University of New South Wales Sydney Australia
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14
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Powell GL, Cabrera-Brown G, Namba MD, Neisewander JL, Marusich JA, Beckmann JS, Gipson CD. Economic demand analysis of within-session dose-reduction during nicotine self-administration. Drug Alcohol Depend 2019; 201:188-196. [PMID: 31238241 PMCID: PMC6639047 DOI: 10.1016/j.drugalcdep.2019.03.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/28/2019] [Accepted: 03/28/2019] [Indexed: 11/18/2022]
Abstract
BACKGROUND This study determined if a within-session dose-reduction design sufficiently captures elasticity of demand for nicotine in male and female rats using environmental enrichment to manipulate demand elasticity. METHODS Male and female Sprague-Dawley rats were trained to self-administer nicotine (60 μg/kg/infusion). In Experiment 1, rats began daily dose-reduction for nine sessions following acquisition. Rats then underwent a minimum of five within-session dose-reduction sessions where each dose was available for 10 min. In Experiment 2, rats were reared in isolated, social, or enriched housing followed by acquisition of nicotine self-administration. Rats then underwent within-session dose-reduction. Housing environments were then switched, followed by additional testing sessions. Consumption was calculated for each dose and exponential demand curves were fit. RESULTS No sex differences in acquisition of nicotine self-administration were detected for either experiment. In experiment 1, demand intensity (Q0; estimated intake if nicotine were freely available), was higher with between- compared to within-session dose-reduction, although elasticity of demand (α; rate of decline in nicotine intake as a function of increasing unit price), was lower. In Experiment 2, animals reared in enrichment had fewer infusions during acquisition compared to animals in isolation. Enriched males had reduced demand intensity compared to both isolated and social males, whereas isolated females had reduced intensity compared to enriched females. CONCLUSIONS The within-session dose-reduction procedure for nicotine self-administration replicated effects of environmental enrichment on consumption behaviors. Additionally, this procedure captured differences in nicotine demand due to sex, laying important groundwork for future translational research on mechanisms of nicotine dependence.
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Affiliation(s)
- Gregory L Powell
- Department of Psychology, Arizona State University, 950 McAllister Ave., Psychology Room 203, Tempe, AZ, 85287 USA; School of Life Sciences, Arizona State University, TEMPE Campus, Mailcode 4701, Tempe, AZ, 85281 USA
| | - Gabriella Cabrera-Brown
- Department of Psychology, Arizona State University, 950 McAllister Ave., Psychology Room 203, Tempe, AZ, 85287 USA
| | - Mark D Namba
- Department of Psychology, Arizona State University, 950 McAllister Ave., Psychology Room 203, Tempe, AZ, 85287 USA
| | - Janet L Neisewander
- School of Life Sciences, Arizona State University, TEMPE Campus, Mailcode 4701, Tempe, AZ, 85281 USA
| | - Julie A Marusich
- Center for Drug Discovery, RTI International, 3040 Cornwallis Rd, Research Triangle Park, NC, 27709 USA.
| | - Joshua S Beckmann
- Department of Psychology, University of Kentucky, 741 S. Limestone, B453 BBSRB, Lexington, KY, 40536 USA.
| | - Cassandra D Gipson
- Department of Psychology, Arizona State University, 950 McAllister Ave., Psychology Room 203, Tempe, AZ, 85287 USA.
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15
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Garcia‐Rivas V, Deroche‐Gamonet V. Not all smokers appear to seek nicotine for the same reasons: implications for preclinical research in nicotine dependence. Addict Biol 2019; 24:317-334. [PMID: 29480575 DOI: 10.1111/adb.12607] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 12/11/2017] [Accepted: 01/15/2018] [Indexed: 01/08/2023]
Abstract
Tobacco use leads to 6 million deaths every year due to severe long-lasting diseases. The main component of tobacco, nicotine, is recognized as one of the most addictive drugs, making smoking cessation difficult, even when 70 percent of smokers wish to do so. Clinical and preclinical studies have demonstrated consistently that nicotine seeking is a complex behavior involving various psychopharmacological mechanisms. Evidence supports that the population of smokers is heterogeneous, particularly as regards the breadth of motives that determine the urge to smoke. Here, we review converging psychological, genetic and neurobiological data from clinical and preclinical studies supporting that the mechanisms controlling nicotine seeking may vary from individual to individual. It appears timely that basic neuroscience integrates this heterogeneity to refine our understanding of the neurobiology of nicotine seeking, as tremendous progress has been made in modeling the various psychopharmacological mechanisms driving nicotine seeking in rodents. For a better understanding of the mechanisms that drive nicotine seeking, we emphasize the need for individual-based research strategies in which nicotine seeking, and eventually treatment efficacy, are determined while taking into account individual variations in the mechanisms of nicotine seeking.
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Affiliation(s)
- Vernon Garcia‐Rivas
- Université de Bordeaux France
- INSERM U1215, Psychobiology of Drug AddictionNeuroCentre Magendie France
| | - Véronique Deroche‐Gamonet
- Université de Bordeaux France
- INSERM U1215, Psychobiology of Drug AddictionNeuroCentre Magendie France
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16
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LeSage MG, Smethells JR, Harris AC. Status and Future Directions of Preclinical Behavioral Pharmacology in Tobacco Regulatory Science. ACTA ACUST UNITED AC 2018; 18:252-274. [PMID: 30214916 DOI: 10.1037/bar0000113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Behavioral pharmacology is a branch of the experimental analysis of behavior that has had great influence in drug addiction research and policy. This paper provides an overview of recent behavioral pharmacology research in the field of tobacco regulatory science, which provides the scientific foundation for the Food and Drug Administration Center for Tobacco Products (FDA CTP) to set tobacco control policies. The rationale and aims of tobacco regulatory science are provided, including the types of preclinical operant behavioral models it deems important for assessing the abuse liability of tobacco products and their constituents. We then review literature relevant to key regulatory actions being considered by the FDA CTP, including regulations over nicotine and menthol content of cigarettes, and conclude with suggesting some directions for future research. The current era of tobacco regulatory science provides great opportunities for behavioral pharmacologists to address the leading cause of preventable death and disease worldwide.
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Affiliation(s)
- Mark G LeSage
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
- Department of Psychology, University of Minnesota
| | - John R Smethells
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
| | - Andrew C Harris
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
- Department of Psychology, University of Minnesota
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17
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Bevins RA, Barrett ST, Huynh YW, Thompson BM, Kwan DA, Murray JE. Experimental analysis of behavior and tobacco regulatory research on nicotine reduction. J Exp Anal Behav 2018; 110:1-10. [PMID: 29869329 DOI: 10.1002/jeab.439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 05/02/2018] [Indexed: 12/19/2022]
Abstract
With the signing of H.R. 1256, the Family Smoking Prevention and Tobacco Control Act, the United States Food and Drug Administration (FDA) gained regulatory authority over the tobacco industry. A notable clause in this Act permits the FDA to regulate nicotine yields. However, they cannot completely remove this addictive constituent from tobacco products. This restriction has prompted the FDA to seek research on the threshold dose of nicotine that does not support dependence. This idea of threshold dose has led to an interesting reframing of scientific questions. For example, some researchers studying nicotine from this regulatory perspective translated the notion of an addiction threshold to a construct thought to play a role in addiction but which can be more readily operationalized. Examples include reinforcement threshold, discrimination threshold, and reinforcer-enhancement threshold. In this Perspective Paper, we highlight the importance of behavioral pharmacology and, specifically, the experimental analysis of behavior to help establish a scientific basis for policy decisions regarding nicotine yields. Recent research, including exemplars provided herein, note vast individual differences in the effects of nicotine at a known dose. Unfortunately, the behavioral and biological factors that contribute to such individual variations remain to be understood. We believe that behavior analysts are uniquely well-positioned to contribute to this understanding.
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Affiliation(s)
| | | | | | | | - David A Kwan
- University of Nebraska - Lincoln, Lincoln, NE, USA
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18
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Smith TT, Rupprecht LE, Denlinger-Apte RL, Weeks JJ, Panas RS, Donny EC, Sved AF. Animal Research on Nicotine Reduction: Current Evidence and Research Gaps. Nicotine Tob Res 2018; 19:1005-1015. [PMID: 28379511 DOI: 10.1093/ntr/ntx077] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 03/31/2017] [Indexed: 01/21/2023]
Abstract
A mandated reduction in the nicotine content of cigarettes may improve public health by reducing the prevalence of smoking. Animal self-administration research is an important complement to clinical research on nicotine reduction. It can fill research gaps that may be difficult to address with clinical research, guide clinical researchers about variables that are likely to be important in their own research, and provide policy makers with converging evidence between clinical and preclinical studies about the potential impact of a nicotine reduction policy. Convergence between clinical and preclinical research is important, given the ease with which clinical trial participants can access nonstudy tobacco products in the current marketplace. Herein, we review contributions of preclinical animal research, with a focus on rodent self-administration, to the science of nicotine reduction. Throughout this review, we highlight areas where clinical and preclinical research converge and areas where the two differ. Preclinical research has provided data on many important topics such as the threshold for nicotine reinforcement, the likelihood of compensation, moderators of the impact of nicotine reduction, the impact of environmental stimuli on nicotine reduction, the impact of nonnicotine cigarette smoke constituents on nicotine reduction, and the impact of nicotine reduction on vulnerable populations. Special attention is paid to current research gaps including the dramatic rise in alternative tobacco products, including electronic nicotine delivery systems (ie, e-cigarettes). The evidence reviewed here will be critical for policy makers as well as clinical researchers interested in nicotine reduction. IMPLICATIONS This review will provide policy makers and clinical researchers interested in nicotine reduction with an overview of the preclinical animal research conducted on nicotine reduction and the regulatory implications of that research. The review also highlights the utility of preclinical research for research questions related to nicotine reduction.
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Affiliation(s)
- Tracy T Smith
- University of Pittsburgh Cancer Institute, Pittsburgh, PA.,Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA
| | - Laura E Rupprecht
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Rachel L Denlinger-Apte
- Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, RI
| | - Jillian J Weeks
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Rachel S Panas
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA
| | - Alan F Sved
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA.,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
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19
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Swain Y, Muelken P, LeSage MG, Gewirtz JC, Harris AC. Locomotor activity does not predict individual differences in morphine self-administration in rats. Pharmacol Biochem Behav 2018; 166:48-56. [PMID: 29409807 DOI: 10.1016/j.pbb.2018.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/31/2018] [Accepted: 01/31/2018] [Indexed: 12/19/2022]
Abstract
Understanding factors contributing to individual differences in opioid addiction vulnerability is essential for developing more effective preventions and treatments. Sensation seeking has been implicated in addiction to several drugs of abuse, yet its relationship with individual differences in opioid addiction vulnerability has not been well established. The primary goal of this study was to evaluate the relationship between locomotor activity in a novel environment, a preclinical model of sensation-seeking, and individual differences in acquisition of i.v. morphine self-administration (SA) in rats. A secondary goal was to evaluate the relationship between activity and elasticity of demand (reinforcing efficacy) for morphine measured using a behavioral economic approach. Following an initial locomotor activity screen, animals were allowed to acquire morphine SA at a unit dose of 0.5 mg/kg/infusion in 4 hour/day sessions (Experiment 1) or 0.2 mg/kg/infusion in 2 hour/day sessions (Experiment 2) until infusion rates were stable. Unit price was subsequently manipulated via progressive reductions in unit dose (Experiment 1) or increases in response requirement per infusion (Experiment 2). Activity levels were not correlated with acquisition of morphine SA in either experiment. Morphine consumption was generally well described by an exponential demand function in both experiments (R2 values > 0.95 for rats as a group), but activity did not correlate with behavioral economic measures. Locomotor activity in a novel environment did not predict individual differences in acquisition of morphine SA. These data complement findings from some human studies and suggest that the role of sensation seeking in individual differences in opioid addiction vulnerability may be limited.
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Affiliation(s)
- Yayi Swain
- Minneapolis Medical Research Foundation, Minneapolis, MN, United States; Department of Psychology, University of Minnesota, Minneapolis, MN, United States
| | - Peter Muelken
- Minneapolis Medical Research Foundation, Minneapolis, MN, United States
| | - Mark G LeSage
- Minneapolis Medical Research Foundation, Minneapolis, MN, United States; Department of Psychology, University of Minnesota, Minneapolis, MN, United States; Department of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Jonathan C Gewirtz
- Department of Medicine, University of Minnesota, Minneapolis, MN, United States; Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Andrew C Harris
- Minneapolis Medical Research Foundation, Minneapolis, MN, United States; Department of Psychology, University of Minnesota, Minneapolis, MN, United States; Department of Medicine, University of Minnesota, Minneapolis, MN, United States.
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20
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Abstract
BACKGROUND Several recent studies have investigated the choice between heroin and a non-drug alternative reinforcer in rats. A common finding in these studies is that there are large individual differences in preference, with some rats preferring heroin and some preferring the non-drug alternative. The primary goal of the present study was to determine whether individual differences in how heroin or saccharin is valued, based on demand analysis, predicts choice. METHODS Rats lever-pressed for heroin infusions and saccharin reinforcers on fixed-ratio schedules. The essential value of each reinforcer was obtained from resulting demand curves. Rats were then trained on a mutually exclusive choice procedure where pressing one lever resulted in heroin and pressing another resulted in saccharin. After seven sessions of increased access to heroin or saccharin, rats were reexposed to the demand and choice procedures. RESULTS Demand for heroin was more elastic than demand for saccharin (i.e., heroin had lower essential value than saccharin). When allowed to choose, most rats preferred saccharin. The essential value of heroin, but not saccharin, predicted preference. The essential value of both heroin and saccharin increased following a week of increased access to heroin, but similar saccharin exposure had no effect on essential value. Preference was unchanged after increased access to either reinforcer. CONCLUSION Heroin-preferring rats differed from saccharin-preferring rats in how they valued heroin, but not saccharin. To the extent that choice models addiction-related behavior, these results suggest that overvaluation of opioids specifically, rather than undervaluation of non-drug alternatives, could identify susceptible individuals.
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Affiliation(s)
| | - Jung S. Kim
- Psychology Department, American University, Washington, DC
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21
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Perkins KA, Kunkle N, Karelitz JL. Threshold dose for behavioral discrimination of cigarette nicotine content in menthol vs. non-menthol smokers. Psychopharmacology (Berl) 2017; 234:1255-1265. [PMID: 28210778 DOI: 10.1007/s00213-017-4563-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/03/2017] [Indexed: 01/01/2023]
Abstract
RATIONALE The lowest threshold content (or "dose") of nicotine discriminated in cigarettes may differ due to menthol preference. OBJECTIVES Menthol and non-menthol Spectrum research cigarettes differing in nicotine content were used to determine discrimination thresholds. METHODS Dependent smokers preferring menthol (n = 40) or non-menthol (n = 21) brands were tested on ability to discriminate cigarettes (matched for their menthol preference) with nicotine contents of 16-17, 11-12, 5, 2, and 1 mg/g, one per session, from an "ultra-low" cigarette with 0.4 mg/g. Controlled exposure to each cigarette was four puffs/trial, and the number of sessions was determined by the lowest nicotine content they could discriminate on >80% of trials (i.e., ≥5 of 6). We also assessed subjective perceptions and behavioral choice between cigarettes to relate them to discrimination responses. RESULTS Controlling for Fagerstrom Test of Nicotine Dependence score, discrimination thresholds were more likely to be at higher nicotine content cigarettes for menthol vs. non-menthol smokers (p < .005), with medians of 16 vs. 11 mg/g, respectively. Compared to the ultra-low, threshold and subthreshold (next lowest) cigarettes differed on most perceptions and puff choice, but menthol preference did not alter these associations. Notably, threshold cigarettes did, but subthreshold did not, increase choice over the ultra-low. CONCLUSIONS Threshold for discriminating nicotine via smoking may be generally higher for menthol vs. non-menthol smokers. More research is needed to identify why menthol smoking is related to higher nicotine thresholds and to verify that cigarettes unable to be discriminated do not support reinforcement.
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Affiliation(s)
- Kenneth A Perkins
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA.
| | - Nicole Kunkle
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
| | - Joshua L Karelitz
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
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22
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Garcia-Rivas V, Cannella N, Deroche-Gamonet V. Individual Variations in the Mechanisms of Nicotine Seeking: A Key for Research on Nicotine Dependence. Neuropsychopharmacology 2017; 42:584-586. [PMID: 27577600 PMCID: PMC5240183 DOI: 10.1038/npp.2016.176] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/24/2016] [Accepted: 08/25/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Vernon Garcia-Rivas
- INSERM U1215, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux, France,University of Bordeaux, Bordeaux, France
| | - Nazzareno Cannella
- INSERM U1215, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux, France,University of Bordeaux, Bordeaux, France
| | - Véronique Deroche-Gamonet
- INSERM U1215, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux, France,University of Bordeaux, Bordeaux, France,INSERM U1215, Pathophysiology of Addiction, Neuro Centre Magendie, 146 rue Léo Saignat, Bordeaux 33077, France, Tel: +33 5 57 57 36 80, Fax: +33 5 57 57 36 69, E-mail:
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23
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Henningfield JE, Smith TT, Kleykamp BA, Fant RV, Donny EC. Nicotine self-administration research: the legacy of Steven R. Goldberg and implications for regulation, health policy, and research. Psychopharmacology (Berl) 2016; 233:3829-3848. [PMID: 27766371 PMCID: PMC5588156 DOI: 10.1007/s00213-016-4441-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 09/15/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND RATIONALE Steven R. Goldberg was a pioneering behavioral pharmacologist whose intravenous drug self-administration studies advanced the understanding of conditioned stimuli and schedules of reinforcement as determinants of pattern and persistence of drug-seeking behavior, and in particular, the importance of nicotine in tobacco use. His passing in 2014 led to invitations to contribute articles to psychopharmacology dedicated to his work. OBJECTIVES The objectives of this review are to summarize and put into historical perspective Goldberg's contributions to elucidate the reinforcing effects of nicotine and to summarize the implications of his research for medication development, tobacco regulation, and potential tobacco control policy options. This includes a review of intravenous nicotine self-administration research from the 1960s to 2016. RESULTS Goldberg's application of behavioral pharmacology methods to investigate nicotine reinforcement and the influence of schedule of reinforcement and conditioned stimuli on nicotine administration contributed to the conclusions of the US National Institute on Drug Abuse, and the Surgeon General, that nicotine met the criteria as a dependence-producing drug and cigarette smoking as a prototypic drug dependency or "addiction." Equally important, this work has been systematically extended to other species and applied to address a range of factors relevant to tobacco use, medication development, regulation, and public health policy. CONCLUSIONS Steven R. Goldberg was a pioneering scientist whose systematic application of the science of behavioral pharmacology advanced the understanding of tobacco and nicotine use and contributed to the scientific foundation for tobacco product regulation and potential public health tobacco control policy development.
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Affiliation(s)
- Jack E Henningfield
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA.
- Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Tracy T Smith
- University of Pittsburgh Cancer Institute, 4120 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 4120 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
| | - Bethea A Kleykamp
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA
| | - Reginald V Fant
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
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24
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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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LeSage MG, Staley M, Muelken P, Smethells JR, Stepanov I, Vogel RI, Pentel PR, Harris AC. Abuse liability assessment of an e-cigarette refill liquid using intracranial self-stimulation and self-administration models in rats. Drug Alcohol Depend 2016; 168:76-88. [PMID: 27627814 PMCID: PMC5257285 DOI: 10.1016/j.drugalcdep.2016.08.628] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/14/2016] [Accepted: 08/22/2016] [Indexed: 01/19/2023]
Abstract
BACKGROUND The popularity of electronic cigarettes (ECs) has increased dramatically despite their unknown health consequences. Because the abuse liability of ECs is one of the leading concerns of the Food and Drug Administration (FDA), models to assess it are urgently needed to inform FDA regulatory decisions regarding these products. The purpose of this study was to assess the relative abuse liability of an EC liquid compared to nicotine alone in rats. Because this EC liquid contains non-nicotine constituents that may enhance its abuse liability, we hypothesized that it would have greater abuse liability than nicotine alone. METHODS Nicotine alone and nicotine dose-equivalent concentrations of EC liquid were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, acquisition of self-administration, reinforcing efficacy (i.e., elasticity of demand), blockade of these behavioral effects by mecamylamine, nicotine pharmacokinetics and nicotinic acetylcholine receptor binding and activation. RESULTS There were no significant differences between formulations on any measure, except that EC liquid produced less of an elevation in ICSS thresholds at high nicotine doses. CONCLUSIONS Collectively, these findings suggest that the relative abuse liability of this EC liquid is similar to that of nicotine alone in terms of its reinforcing and reinforcement-enhancing effects, but that it may have less aversive/anhedonic effects at high doses. The present methods may be useful for assessing the abuse liability of other ECs to inform potential FDA regulation of those products.
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Affiliation(s)
- MG LeSage
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN,Department of Psychology, University of Minnesota, Minneapolis, MN, 55455
| | - M Staley
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN
| | - P Muelken
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN
| | - JR Smethells
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Psychiatry, University of Minnesota, Minneapolis, MN, 55455
| | - I Stepanov
- Masonic Cancer, Center University of Minnesota, Minneapolis, MN
| | - RI Vogel
- Masonic Cancer Center Biostatistics and Bioinformatics Core ,University of Minnesota Minneapolis, MN
| | - PR Pentel
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN
| | - AC Harris
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN,Department of Psychology, University of Minnesota, Minneapolis, MN, 55455
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Abstract
OBJECTIVE Preclinical abuse liability assessment is an essential component of tobacco regulatory science. The goal of this project was to evaluate the relative abuse liability of smokeless tobacco products in rats using aqueous extracts of those products. These extracts provide exposure to an extensive range of nicotine and non-nicotine tobacco constituents as occurs in humans. METHODS Rats were trained to self-administer either nicotine alone or extracts of Camel Snus or Kodiak smokeless tobacco at an equivalent nicotine unit dose. In Experiment 1, the relative reinforcing efficacy of these formulations was assessed in adults and adolescents using a progressive ratio schedule under limited-access conditions. In Experiment 2, relative reinforcing efficacy was assessed in adolescents under unlimited-access conditions using behavioral economic demand curve analysis. RESULTS The reinforcing efficacy of nicotine formulations was higher in adolescents than adults, but no difference was observed between formulations in either age group. Similarly, there was no difference in elasticity of demand between formulations in adolescents. CONCLUSIONS The present findings suggest that the abuse liability of these smokeless tobacco products is similar to nicotine alone, and that nicotine dose is the primary determinant of the reinforcing efficacy of systemic exposure to these products.
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Perkins KA, Kunkle N, Karelitz JL, Michael VC, Donny EC. Threshold dose for discrimination of nicotine via cigarette smoking. Psychopharmacology (Berl) 2016; 233:2309-17. [PMID: 27037937 PMCID: PMC4873331 DOI: 10.1007/s00213-016-4281-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/17/2016] [Indexed: 12/28/2022]
Abstract
RATIONALE The lowest nicotine threshold "dose" in cigarettes discriminated from a cigarette containing virtually no nicotine may help inform the minimum dose maintaining dependence. OBJECTIVES Spectrum research cigarettes (from NIDA) differing in nicotine content were used to evaluate a procedure to determine discrimination thresholds. METHODS Dependent smokers (n = 18; 13 M, 5 F) were tested on ability to discriminate cigarettes with nicotine contents of 11, 5, 2.4, and 1.3 mg/g, one per session, from the "ultralow" cigarette with 0.4 mg/g, after having discriminated 16 mg/g from 0.4 mg/g (all had 9-10 mg "tar"). Exposure to each was limited to 4 puffs/trial. All subjects were abstinent from smoking overnight prior to each session, and the number of sessions was determined by the participant's success in discrimination behavior on >80 % of trials. Subjective perceptions and behavioral choice between cigarettes were also assessed and related to discrimination behavior. RESULTS The median threshold was 11 mg/g, but the range was 2.4 to 16 mg/g, suggesting wide variability in discrimination threshold. Compared to the ultralow, puff choice was greater for the subject's threshold dose but only marginal for the subthreshold (next lowest nicotine) cigarette. Threshold and subthreshold also differed on subjective perceptions but not withdrawal relief. CONCLUSIONS Under these testing conditions, threshold content for discriminating nicotine via cigarettes may be 11 mg/g or greater for most smokers, but some can discriminate nicotine contents one-half or one-quarter this amount. Further study with other procedures and cigarette exposure amounts may identify systematic differences in nicotine discrimination thresholds.
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Affiliation(s)
- Kenneth A Perkins
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA.
| | - Nicole Kunkle
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
| | - Joshua L Karelitz
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
| | - Valerie C Michael
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA, 15213, USA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet St., Pittsburgh, PA, 15260, USA
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A Two-Day Continuous Nicotine Infusion Is Sufficient to Demonstrate Nicotine Withdrawal in Rats as Measured Using Intracranial Self-Stimulation. PLoS One 2015; 10:e0144553. [PMID: 26658557 PMCID: PMC4684239 DOI: 10.1371/journal.pone.0144553] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/19/2015] [Indexed: 01/23/2023] Open
Abstract
Avoidance of the negative affective (emotional) symptoms of nicotine withdrawal (e.g., anhedonia, anxiety) contributes to tobacco addiction. Establishing the minimal nicotine exposure conditions required to demonstrate negative affective withdrawal signs in animals, as well as understanding moderators of these conditions, could inform tobacco addiction-related research, treatment, and policy. The goal of this study was to determine the minimal duration of continuous nicotine infusion required to demonstrate nicotine withdrawal in rats as measured by elevations in intracranial self-stimulation (ICSS) thresholds (anhedonia-like behavior). Administration of the nicotinic acetylcholine receptor antagonist mecamylamine (3.0 mg/kg, s.c.) on alternate test days throughout the course of a 2-week continuous nicotine infusion (3.2 mg/kg/day via osmotic minipump) elicited elevations in ICSS thresholds beginning on the second day of infusion. Magnitude of antagonist-precipitated withdrawal did not change with further nicotine exposure and mecamylamine injections, and was similar to that observed in a positive control group receiving mecamylamine following a 14-day nicotine infusion. Expression of a significant withdrawal effect was delayed in nicotine-infused rats receiving mecamylamine on all test days rather than on alternate test days. In a separate study, rats exhibited a transient increase in ICSS thresholds following cessation of a 2-day continuous nicotine infusion (3.2 mg/kg/day). Magnitude of this spontaneous withdrawal effect was similar to that observed in rats receiving a 9-day nicotine infusion. Our findings demonstrate that rats exhibit antagonist-precipitated and spontaneous nicotine withdrawal following a 2-day continuous nicotine infusion, at least under the experimental conditions studied here. Magnitude of these effects were similar to those observed in traditional models involving more prolonged nicotine exposure. Further development of these models, including evaluation of more clinically relevant nicotine dosing regimens and other measures of nicotine withdrawal (e.g., anxiety-like behavior, somatic signs), may be useful for understanding the development of the nicotine withdrawal syndrome.
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