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Algallal HE, Jacquemet V, Samaha AN. Intermittent nicotine access is as effective as continuous access in promoting nicotine seeking and taking in rats. Psychopharmacology (Berl) 2024; 241:1135-1149. [PMID: 38326505 DOI: 10.1007/s00213-024-06546-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 01/20/2024] [Indexed: 02/09/2024]
Abstract
RATIONALE Nicotine is a principal psychoactive agent in tobacco, contributing to tobacco's addictive potential. Preclinical studies on the effects of voluntary nicotine intake typically use self-administration procedures that provide continuous nicotine access during each self-administration session. However, many smokers consume cigarettes intermittently rather than continuously throughout each day. For drugs including cocaine and opioids, research in laboratory rats shows that intermittent intake can be more effective than continuous intake in producing patterns of drug use relevant to addiction. OBJECTIVE We determined how intermittent versus continuous nicotine self-administration influences nicotine seeking and taking behaviours. METHODS Female and male rats had continuous (i.e., Long Access; LgA, 6 h/day) or intermittent (IntA; 12 min ON, 60 min OFF, for 6 h/day) access to intravenous nicotine (15 µg/kg/infusion), for 12 daily sessions. We then assessed intake, responding for nicotine under a progressive ratio schedule of drug reinforcement and cue- and nicotine-induced reinstatement of drug seeking. We also estimated nicotine pharmacokinetic parameters during LgA and IntA self-administration. RESULTS Overall, LgA rats took twice more nicotine than did IntA rats, yielding more sustained increases in estimated brain concentrations of the drug. However, the two groups showed similar motivation to seek and take nicotine, as measured using reinstatement and progressive ratio procedures, respectively. CONCLUSIONS Intermittent nicotine use is just as effective as continuous use in producing addiction-relevant behaviours, despite significantly less nicotine exposure. This has implications for modeling nicotine self-administration patterns in human smokers and resulting effects on brain and behaviour.
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Affiliation(s)
- Hajer E Algallal
- Biomedical Sciences, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Vincent Jacquemet
- Institute of Biomedical Engineering, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada
| | - Anne-Noël Samaha
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montreal, QC, H3C 3J7, Canada.
- Neural Signaling and Circuitry Research Group (SNC), Faculty of Medicine, Université de Montréal, Montreal, QC, Canada.
- Center for Interdisciplinary Research On the Brain and Learning (CIRCA), Université de Montréal, Montreal, QC, Canada.
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2
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Frie JA, McCunn P, Eed A, Hassan A, Luciani KR, Chen C, Tyndale RF, Khokhar JY. Factors influencing JUUL e-cigarette nicotine vapour-induced reward, withdrawal, pharmacokinetics and brain connectivity in rats: sex matters. Neuropsychopharmacology 2024; 49:782-795. [PMID: 38057369 PMCID: PMC10948865 DOI: 10.1038/s41386-023-01773-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 11/05/2023] [Accepted: 11/14/2023] [Indexed: 12/08/2023]
Abstract
Though vaping likely represents a safer alternative to smoking, it is not without risks, many of which are not well understood, especially for vulnerable populations. Here we evaluate the sex- and age-dependent effects of JUUL nicotine vapour in rats. Following passive nicotine vapour exposures (from 59 mg/ml JUUL nicotine pods), rats were evaluated for reward-like behaviour, locomotion, and precipitated withdrawal. Pharmacokinetics of nicotine and its metabolites in brain and plasma and the long-term impact of nicotine vapour exposure on functional magnetic resonance imaging-based brain connectivity were assessed. Adult female rats acquired conditioned place preference (CPP) at a high dose (600 s of exposure) of nicotine vapour while female adolescents, as well as male adults and adolescents did not. Adult and adolescent male rats displayed nicotine vapour-induced precipitated withdrawal and hyperlocomotion, while both adult and adolescent female rats did not. Adult females showed higher venous and arterial plasma and brain nicotine and nicotine metabolite concentrations compared to adult males and adolescent females. Adolescent females showed higher brain nicotine concentration compared to adolescent males. Both network-based statistics and between-component group connectivity analyses uncovered reduced connectivity in nicotine-exposed rats, with a significant group by sex interaction observed in both analyses. The short- and long-term effects of nicotine vapour are affected by sex and age, with distinct behavioural, pharmacokinetic, and altered network connectivity outcomes dependent on these variables.
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Affiliation(s)
- Jude A Frie
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Patrick McCunn
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Amr Eed
- Department of Medical Biophysics and Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Ahmad Hassan
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Karling R Luciani
- Department of Psychiatry, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Chuyun Chen
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Rachel F Tyndale
- Departments of Psychiatry, and Pharmacology & Toxicology, University of Toronto, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Jibran Y Khokhar
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
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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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Chellian R, Behnood-Rod A, Wilson R, Lin K, Wing-Yan King G, Bruijnzeel AW. The D1/D2-like receptor antagonist flupentixol and the D2-like receptor antagonist L-741626 decrease operant responding for nicotine and food and locomotor activity in male and female rats. J Psychopharmacol 2023; 37:216-228. [PMID: 36680471 DOI: 10.1177/02698811221147141] [Citation(s) in RCA: 3] [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] [Indexed: 01/22/2023]
Abstract
BACKGROUND The reinforcing properties of nicotine play a critical role in smoking and vaping. There is a need for treatments that decrease the reinforcing properties of nicotine and thereby improve smoking and vaping rates. Dopamine plays a role in the reinforcing properties of nicotine, but little is known about the role of dopamine D2-like receptors in nicotine intake and whether there are sex differences in the effects of dopaminergic drugs on nicotine intake. AIM The goal of the present studies was to investigate the effects of the D1/D2-like receptor antagonist flupentixol and the D2-like receptor antagonist L-741626 on nicotine self-administration in male and female rats. METHODS The effects of flupentixol and L-741626 on operant responding for nicotine and food and locomotor activity in a small open field were investigated. RESULTS There were no sex differences in baseline nicotine intake. The D1/D2-like receptor antagonist flupentixol and the D2-like receptor antagonist L-741626 decreased operant responding for nicotine. Blockade of D1/D2-like receptors and blockade of D2-like receptors also decreased operant responding for food and decreased locomotor activity. Flupentixol induced a greater decrease in operant responding for food in males than females. However, in the other tests, there were no sex differences in the effects of the dopamine receptor antagonists. CONCLUSIONS Blockade of D1/D2-like receptors with flupentixol and D2-like receptors with L-741626 decreases nicotine and food intake in rats of both sexes. These compounds also decrease locomotor activity which might be indicative of a sedative effect.
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Affiliation(s)
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Karen Lin
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
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Chellian R, Behnood-Rod A, Wilson R, Lin K, King GWY, Ruppert-Gomez M, Teter AN, Febo M, Bruijnzeel AW. Dopamine D1-like receptor blockade and stimulation decreases operant responding for nicotine and food in male and female rats. Sci Rep 2022; 12:14131. [PMID: 35986048 PMCID: PMC9388990 DOI: 10.1038/s41598-022-18081-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 08/04/2022] [Indexed: 11/09/2022] Open
Abstract
Dopamine has been implicated in the reinforcing effects of smoking. However, there remains a need for a better understanding of the effects of dopamine D1-like receptor agonists on nicotine intake and the role of sex differences in the effects of dopaminergic drugs on behavior. This work studied the effects of D1-like receptor stimulation and blockade on operant responding for nicotine and food and locomotor activity in male and female rats. The effects of the D1-like receptor antagonist SCH 23390 (0.003, 0.01, 0.03 mg/kg) and the D1-like receptor agonist A77636 (0.1, 0.3, 1 mg/kg) on responding for nicotine and food, and locomotor activity were investigated. The effects of SCH 23390 were investigated 15 min and 24 h after treatment, and the effects of the long-acting drug A77636 were investigated 15 min, 24 h, and 48 h after treatment. Operant responding for nicotine and food and locomotor activity were decreased immediately after treatment with SCH 23390. Treatment with SCH 23390 did not have any long-term effects. Operant responding for nicotine was still decreased 48 h after treatment with A77636, and food responding was decreased up to 24 h after treatment. Treatment with A77636 only decreased locomotor activity at the 48 h time point. There were no sex differences in the effects of SCH 23390 or A77636. In conclusion, the D1-like receptor antagonist SCH 23390 reduces nicotine intake and causes sedation in rats. Stimulation of D1-like receptors with A77636 decreases nicotine intake at time points that the drug does not cause sedation.
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Affiliation(s)
- Ranjithkumar Chellian
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Karen Lin
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Grace Wing-Yan King
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Marcella Ruppert-Gomez
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Alexandria Nicole Teter
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Marcelo Febo
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA.
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Marrero-Cristobal G, Gelpi-Dominguez U, Morales-Silva R, Alvarado-Torres J, Perez-Torres J, Perez-Perez Y, Sepulveda-Orengo M. Aerobic exercise as a promising nonpharmacological therapy for the treatment of substance use disorders. J Neurosci Res 2022; 100:1602-1642. [PMID: 34850988 PMCID: PMC9156662 DOI: 10.1002/jnr.24990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 10/06/2021] [Accepted: 10/14/2021] [Indexed: 12/12/2022]
Abstract
Despite the prevalence and public health impact of substance use disorders (SUDs), effective long-term treatments remain elusive. Aerobic exercise is a promising, nonpharmacological treatment currently under investigation as a strategy for preventing drug relapse. Aerobic exercise could be incorporated into the comprehensive treatment regimens for people with substance abuse disorders. Preclinical studies of SUD with animal models have shown that aerobic exercise diminishes drug-seeking behavior, which leads to relapse, in both male and female rats. Nevertheless, little is known regarding the effects of substance abuse-induced cellular and physiological adaptations believed to be responsible for drug-seeking behavior. Accordingly, the overall goal of this review is to provide a summary and an assessment of findings to date, highlighting evidence of the molecular and neurological effects of exercise on adaptations associated with SUD.
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Affiliation(s)
| | - Ursula Gelpi-Dominguez
- School of Behavioral and Brain Sciences, Ponce Health Sciences University, Ponce, PR, USA
| | - Roberto Morales-Silva
- Department of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR, USA
| | - John Alvarado-Torres
- Department of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR, USA
| | - Joshua Perez-Torres
- Department of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR, USA
| | - Yobet Perez-Perez
- Department of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR, USA
| | - Marian Sepulveda-Orengo
- Department of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR, USA
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Sex Differences in Psychostimulant Abuse: Implications for Estrogen Receptors and Histone Deacetylases. Genes (Basel) 2022; 13:genes13050892. [PMID: 35627277 PMCID: PMC9140379 DOI: 10.3390/genes13050892] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 02/04/2023] Open
Abstract
Substance abuse is a chronic pathological disorder that negatively affects many health and neurological processes. A growing body of literature has revealed gender differences in substance use. Compared to men, women display distinct drug-use phenotypes accompanied by recovery and rehabilitation disparities. These observations have led to the notion that sex-dependent susceptibilities exist along the progression to addiction. Within this scope, neuroadaptations following psychostimulant exposure are thought to be distinct for each sex. This review summarizes clinical findings and animal research reporting sex differences in the subjective and behavioral responses to cocaine, methamphetamine, and nicotine. This discussion is followed by an examination of epigenetic and molecular alterations implicated in the addiction process. Special consideration is given to histone deacetylases and estrogen receptor-mediated gene expression.
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Effects of NMDA receptor antagonists on behavioral economic indices of cocaine self-administration. Drug Alcohol Depend 2022; 233:109348. [PMID: 35176632 PMCID: PMC8957596 DOI: 10.1016/j.drugalcdep.2022.109348] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/21/2022] [Accepted: 02/07/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND Currently, there are no FDA-approved medications for the treatment of psychostimulant (e.g., cocaine) use disorders. Because the GluN2B subunit of the glutamate N-methyl-D-aspartate (NMDA) receptor is an important mediator of addiction-like behaviors, the goal of the current study was to determine if the GluN2B-selective antagonist Ro 63-1908 is efficacious in attenuating cocaine self-administration. METHODS Adult Sprague Dawley rats (24 males and 11 females) were implanted with indwelling catheters and were trained to self-administer cocaine (0.75 mg/kg/inf). Rats were then trained in a threshold procedure, in which the dose of cocaine decreased across six 6-min blocks (0.75, 0.27, 0.08, 0.03, 0.01, 0.003 mg/kg/inf). This procedure allowed for the quantification of behavioral economic indices of drug self-administration. Following training in the threshold procedure, rats were treated with the GluN2B-selective antagonist Ro 63-1908 (0, 0.1, 0.3, 1.0 mg/kg; s.c.). Rats also received treatments of the NMDA receptor channel blocker MK-801 (0, 0.01, 0.03, 0.06 mg/kg; s.c.). RESULTS Blocking NMDA receptors decreased initial intake (i.e., consumption during the first block), although Ro 63-1908 and MK-801 increased area under the curve (global measure of demand) and decreased demand elasticity, an effect observed primarily in males. Neither drug affected demand intensity (i.e., consumption of cocaine at a minimally constrained price). CONCLUSIONS While blocking the NMDA receptor decreases initial intake of cocaine, NMDA receptor antagonists make cocaine more inelastic with increasing price. These results suggest that NMDA receptor antagonists can exacerbate addiction-like behaviors during self-administration during extinction-like conditions that are observed in later blocks of the threshold procedure.
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9
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Moen JK, Lee AM. Sex Differences in the Nicotinic Acetylcholine Receptor System of Rodents: Impacts on Nicotine and Alcohol Reward Behaviors. Front Neurosci 2021; 15:745783. [PMID: 34621155 PMCID: PMC8490611 DOI: 10.3389/fnins.2021.745783] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 08/31/2021] [Indexed: 12/20/2022] Open
Abstract
Alcohol and nicotine are the two most widely used and misused drugs around the world, and co-consumption of both substances is highly prevalent. Multiple lines of evidence show a profound effect of sex in many aspects of alcohol and nicotine reward, with women having more difficulty quitting smoking and showing a faster progression toward developing alcohol use disorder compared with men. Both alcohol and nicotine require neuronal nicotinic acetylcholine receptors (nAChRs) to elicit rewarding effects within the mesolimbic system, representing a shared molecular pathway that likely contributes to the frequent comorbidity of alcohol and nicotine dependence. However, the majority of preclinical studies on the mechanisms of alcohol and nicotine reward behaviors utilize only male rodents, and thus our understanding of alcohol and nicotine neuropharmacology relies heavily on male data. As preclinical research informs the development and refinement of therapies to help patients reduce drug consumption, it is critical to understand the way biological sex and sex hormones influence the rewarding properties of alcohol and nicotine. In this review, we summarize what is known about sex differences in rodent models of alcohol and nicotine reward behaviors with a focus on neuronal nAChRs, highlighting exciting areas for future research. Additionally, we discuss the way circulating sex hormones may interact with neuronal nAChRs to influence reward-related behavior.
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Affiliation(s)
- Janna K Moen
- Graduate Program in Neuroscience, University of Minnesota Twin Cities, Minneapolis, MN, United States
| | - Anna M Lee
- Graduate Program in Neuroscience, University of Minnesota Twin Cities, Minneapolis, MN, United States.,Department of Pharmacology, University of Minnesota Twin Cities, Minneapolis, MN, United States
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Leyrer-Jackson JM, Overby PF, Bull A, Marusich JA, Gipson CD. Strain and sex matters: Differences in nicotine self-administration between outbred and recombinase-driver transgenic rat lines. Exp Clin Psychopharmacol 2021; 29:375-384. [PMID: 32297781 PMCID: PMC8375641 DOI: 10.1037/pha0000376] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Preclinical studies of nicotine self-administration provide important value for the field as they are highly rigorous, controlled, can be conducted quickly, and are generalizable to humans. Given the translational value of the nicotine self-administration model, and the relatively new guidelines of the National Institutes of Health to include sex as a biological variable, strain and sex differences in nicotine acquisition were examined here in two outbred rat strains. Sprague-Dawley (SD) and Long-Evans (LE; wildtype and cholinergic acetyltransferase cre-recombinase transgenic) rats of each sex were implanted with indwelling intravenous jugular catheters. Rats were trained to self-administer nicotine (0.02 mg/kg per infusion, paired with contingent light + tone stimuli). Acquisition criteria were set at a minimum active:inactive response ratio of 2:1 and a minimum of 10 infusions per session, both of which had to be met for a minimum of 10 sessions. Across 10 sessions, male SD rats self-administered significantly more nicotine than female SD rats (p < .05), indicating a sex difference in this strain. LE females self-administered more nicotine than SD females indicative of a strain difference between females (p < .05). SD males increased nicotine infusions across sessions compared to LE males and SD females (p < .05). No strain or sex differences were observed in the number of sessions to reach criteria. No differences between wildtype and transgenic LE rats were observed. These results demonstrate sex and strain differences in nicotine self-administration between SD and LE rats and may lend insight into development of other nicotine self-administration models, where sex and strain may impact acquisition. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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Affiliation(s)
| | - Paula F. Overby
- Department of Psychology, Arizona State University, Tempe, Arizona, USA
| | - Amanda Bull
- Department of Psychology, Arizona State University, Tempe, Arizona, USA
| | - Julie A. Marusich
- Center for Drug Discovery, RTI International, Research Triangle Park, North Carolina, USA
| | - Cassandra D. Gipson
- Department of Family and Community Medicine, University of Kentucky, Lexington Kentucky, USA
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Adolescent nicotine treatment causes robust locomotor sensitization during adolescence but impedes the spontaneous acquisition of nicotine intake in adult female Wistar rats. Pharmacol Biochem Behav 2021; 207:173224. [PMID: 34197844 DOI: 10.1016/j.pbb.2021.173224] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 11/20/2022]
Abstract
Very few people are able to quit smoking, and therefore it is essential to know which factors contribute to the development of compulsive nicotine use. These studies aimed to investigate if early-adolescent nicotine exposure causes locomotor sensitization and affects anxiety-like behavior and the spontaneous acquisition of intravenous nicotine self-administration. Early-adolescent male and female rats were treated with nicotine from postnatal (P) days 24 to 42, and anxiety-like behavior and locomotor activity were investigated one day after the cessation of nicotine treatment and in adulthood (>P75). The spontaneous acquisition of nicotine self-administration was also investigated in adulthood. The rats self-administered 0.03 mg/kg/infusion of nicotine for six days under a fixed-ratio (FR) 1 schedule and four days under an FR2 schedule (3-h sessions). Repeated nicotine administration increased locomotor activity, rearing, and stereotypies in a small open field in adolescent male and female rats. One day after the last nicotine injection, the percentage of open arm entries in the elevated plus-maze test was decreased in the males and increased in the females. However, locomotor activity in the small open field was unaffected. Adolescent nicotine treatment did not affect anxiety-like behavior and locomotor activity in adulthood. During the 10-day nicotine self-administration period, the females had a higher level of nicotine intake than the males. Adolescent nicotine treatment decreased nicotine intake in the females. In conclusion, these findings indicate that repeated nicotine administration during adolescence causes robust behavioral sensitization and leads to lower nicotine intake in females throughout the acquisition period in adulthood in rats.
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12
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Swain Y, Gewirtz JC, Harris AC. Behavioral predictors of individual differences in opioid addiction vulnerability as measured using i.v. self-administration in rats. Drug Alcohol Depend 2021; 221:108561. [PMID: 33588371 PMCID: PMC8048102 DOI: 10.1016/j.drugalcdep.2021.108561] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/02/2021] [Accepted: 01/04/2021] [Indexed: 12/22/2022]
Abstract
BACKGROUND Like other forms of psychopathology, vulnerability to opioid addiction is subject to wide individual differences. Animal behavioral models are valuable in advancing our understanding of mechanisms underlying vulnerability to the disorder's development and amenability to treatment. METHODS This review provides an overview of preclinical work on behavioral predictors of opioid addiction vulnerability as measured using the intravenous (i.v.) self-administration (SA) model in rats. We also highlight several new approaches to studying individual differences in opioid addiction vulnerability in preclinical models that could have greater sensitivity and lead to more clinically relevant findings. RESULTS AND CONCLUSIONS Evidence for the relationship between various behavioral traits and opioid SA in the preclinical literature is limited. With the possible exceptions of sensitivity to opioid agonist/withdrawal effects and stress reactivity, predictors of individual differences in SA of other drugs of abuse (e.g. sensation-seeking, impulsivity) do not predict vulnerability to opioid SA in rats. Refinement of SA measures and the use of multivariate designs and statistics could help identify predictors of opioid SA and lead to more clinically relevant studies on opioid addiction vulnerability.
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Affiliation(s)
- Yayi Swain
- Departments of Psychology, University of Minnesota, United States; Hennepin Healthcare Research Institute, United States
| | | | - Andrew C Harris
- Departments of Psychology, University of Minnesota, United States; Hennepin Healthcare Research Institute, United States; Departments of Medicine, University of Minnesota, United States.
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13
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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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14
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Harris AC, Muelken P, LeSage MG. β-Carbolines found in cigarette smoke elevate intracranial self-stimulation thresholds in rats. Pharmacol Biochem Behav 2020; 198:173041. [PMID: 32926882 PMCID: PMC7554228 DOI: 10.1016/j.pbb.2020.173041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/25/2022]
Abstract
Identifying novel constituents that contribute to tobacco addiction is essential for developing more effective treatments and informing FDA regulation of tobacco products. While preclinical data indicate that monoamine oxidase (MAO) inhibitors can have abuse liability or potentiate the addiction-related effects of nicotine, most of these studies have used clinical MAO inhibitors (e.g., tranylcypromine) that are not present in cigarette smoke. The primary goal of this study was to evaluate the abuse potential of the β-carbolines harmane, norharmane, and harmine - MAO inhibitors that are found in cigarette smoke - in an intracranial self-simulation (ICSS) model in rats. A secondary goal was to evaluate the ability of norharmane to influence nicotine's acute effects on ICSS. None of the β-carbolines lowered ICSS thresholds at any dose studied when administered alone, suggesting a lack of abuse liability. Rather, all three β-carbolines produced dose-dependent elevations in ICSS thresholds, indicating aversive/anhedonic effects. Harmane and harmine also elevated ICSS response latencies, suggesting a disruption of motor function, albeit with reduced potency compared to their ICSS threshold-elevating effects. Norharmane (2.5 mg/kg) modestly attenuated the effects of nicotine on ICSS thresholds. Our findings indicate that these β-carbolines produced only aversive/anhedonic effects in an ICSS model when administered alone, and that norharmane unexpectedly attenuated nicotines acute effects on ICSS. Future work evaluating the addiction-related effects of nicotine combined with these and other MAO inhibitors present in smoke may be useful for understanding the role of MAO inhibition in tobacco addiction and informing FDA tobacco regulation.
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Affiliation(s)
- Andrew C Harris
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States of America; Department of Psychology, University of Minnesota, Minneapolis, MN, United States of America.
| | - Peter Muelken
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America
| | - Mark G LeSage
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States of America; Department of Psychology, University of Minnesota, Minneapolis, MN, United States of America
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15
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Chellian R, Wilson R, Polmann M, Knight P, Behnood-Rod A, Bruijnzeel AW. Evaluation of Sex Differences in the Elasticity of Demand for Nicotine and Food in Rats. Nicotine Tob Res 2020; 22:925-934. [PMID: 31603225 DOI: 10.1093/ntr/ntz171] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/04/2019] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Animal studies can inform policy regarding nicotine levels in tobacco products and e-cigarette solutions. Increasing the price of nicotine-containing products decreases their use, but it is unknown how the relationship between price and consumption is affected by both sex and nicotine dose. METHODS A behavioral economics procedure was used to determine the demand elasticity for nicotine in male and female rats. Demand elasticity describes the relationship between price and consumption. A high level of elasticity indicates that consumption is relatively sensitive to increases in price. The rats self-administered a low dose (0.01 mg/kg/inf) or a standard dose (0.03 mg/kg/inf) of nicotine for 9 days under a fixed-ratio (FR) 1 schedule. Then the price (FR schedule) of nicotine was increased, and a demand analysis was conducted. A similar study was conducted with palatable food pellets. RESULTS There were no sex differences in nicotine or food intake under the FR1 schedule. However, demand for 0.03 mg/kg/inf of nicotine was more elastic in females than males. Demand for 0.01 mg/kg/inf of nicotine and food was more elastic in males than females. CONCLUSIONS These findings indicate that there are no differences in nicotine and food intake between males and females when the price is low. When the price of nicotine or food is increased, males maintain their old level of intake longer than females when they have access to a standard dose of nicotine, and females maintain their intake longer when they have access to a low dose of nicotine or food. IMPLICATIONS This behavioral economics analysis indicates that there is no sex difference in nicotine intake when the price of nicotine is low. Increasing the price of nicotine decreases nicotine intake in a dose- and sex-specific manner. Males maintain their old level of intake longer when they have access to a standard dose of nicotine and females when they have access to a low dose. This has implications for tobacco regulatory policy. In a regulatory environment where only low nicotine-containing products are allowed, increasing the price of nicotine products may lead to a greater decrease in nicotine use in males than females.
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Affiliation(s)
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Michaela Polmann
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Parker Knight
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
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Xue S, Behnood-Rod A, Wilson R, Wilks I, Tan S, Bruijnzeel AW. Rewarding Effects of Nicotine in Adolescent and Adult Male and Female Rats as Measured Using Intracranial Self-stimulation. Nicotine Tob Res 2020; 22:172-179. [PMID: 30452710 DOI: 10.1093/ntr/nty249] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/14/2018] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Tobacco is highly addictive, and after the development of dependence, it is difficult to quit smoking. Therefore, it is important to understand the factors that play a role in the initiation of smoking. The rewarding effects of nicotine play a role in the initiation of smoking and the goal of the present study was to determine the rewarding effects of nicotine in adolescent and adult male and female rats. METHODS Male and female Wistar rats were prepared with intracranial self-stimulation (ICSS) electrodes between postnatal day (P) 23 and 33. They were then trained on the ICSS procedure and the effect of nicotine (0, 0.03, 0.1, 0.3 mg/kg) on the reward thresholds and response latencies was investigated during adolescence (P40-59) or adulthood (>P75). RESULTS Nicotine lowered the brain reward thresholds of the adult and adolescent male and female rats. The nicotine-induced decrease in the reward thresholds was the same in the adult male and adult female rats. However, nicotine induced a greater decrease in the reward thresholds of the adolescent female rats than the adolescent male rats. Nicotine decreased the response latencies of all groups and there was no effect of age or sex. CONCLUSIONS Nicotine enhances reward function and psychomotor performance in adolescent and adult male and female rats. Adolescent female rats are more sensitive to the acute rewarding effects of nicotine than adolescent male rats. Therefore, the rewarding effects of nicotine might play a greater role in the initiation of smoking in adolescent females than in adolescent males. IMPLICATIONS The great majority of people start smoking during adolescence. The present studies suggest that during this period female rats are more sensitive to the acute rewarding effects of low and intermediate doses of nicotine than male rats. The rewarding properties of nicotine play a role in the initiation of smoking and establishing habitual smoking. Therefore, the present findings might explain why adolescent females are at a higher risk for becoming nicotine dependent than adolescent males.
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Affiliation(s)
- Song Xue
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Isaac Wilks
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Sijie Tan
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Histology and Embryology, University of South China, Hengyang, Hunan, China
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
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17
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Koul S, Schaal VL, Chand S, Pittenger ST, Nanoth Vellichirammal N, Kumar V, Guda C, Bevins RA, Yelamanchili SV, Pendyala G. Role of Brain Derived Extracellular Vesicles in Decoding Sex Differences Associated with Nicotine Self-Administration. Cells 2020; 9:cells9081883. [PMID: 32796722 PMCID: PMC7464419 DOI: 10.3390/cells9081883] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/04/2020] [Accepted: 08/06/2020] [Indexed: 02/06/2023] Open
Abstract
Smoking remains a significant health and economic concern in the United States. Furthermore, the emerging pattern of nicotine intake between sexes further adds a layer of complexity. Nicotine is a potent psychostimulant with a high addiction liability that can significantly alter brain function. However, the neurobiological mechanisms underlying nicotine’s impact on brain function and behavior remain unclear. Elucidation of these mechanisms is of high clinical importance and may lead to improved therapeutics for smoking cessation. To fill in this critical knowledge gap, our current study focused on identifying sex-specific brain-derived extracellular vesicles (BDEV) signatures in male and female rats post nicotine self-administration. Extracellular vesicles (EVs) are comprised of phospholipid nanovesicles such as apoptotic bodies, microvesicles (MVs), and exosomes based on their origin or size. EVs are garnering significant attention as molecules involved in cell–cell communication and thus regulating the pathophysiology of several diseases. Interestingly, females post nicotine self-administration, showed larger BDEV sizes, along with impaired EV biogenesis compared to males. Next, using quantitative mass spectrometry-based proteomics, we identified BDEV signatures, including distinct molecular pathways, impacted between males and females. In summary, this study has identified sex-specific changes in BDEV biogenesis, protein cargo signatures, and molecular pathways associated with long-term nicotine self-administration.
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Affiliation(s)
- Sneh Koul
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (S.K.); (V.L.S.); (S.C.); (S.V.Y.)
| | - Victoria L. Schaal
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (S.K.); (V.L.S.); (S.C.); (S.V.Y.)
| | - Subhash Chand
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (S.K.); (V.L.S.); (S.C.); (S.V.Y.)
| | - Steven T. Pittenger
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (S.T.P.); (R.A.B.)
| | - Neetha Nanoth Vellichirammal
- Department of Genetics Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; (N.N.V.); (C.G.)
| | - Vikas Kumar
- Mass Spectrometry and Proteomics Core Facility, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Chittibabu Guda
- Department of Genetics Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; (N.N.V.); (C.G.)
| | - Rick A. Bevins
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (S.T.P.); (R.A.B.)
| | - Sowmya V. Yelamanchili
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (S.K.); (V.L.S.); (S.C.); (S.V.Y.)
| | - Gurudutt Pendyala
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE 68198, USA; (S.K.); (V.L.S.); (S.C.); (S.V.Y.)
- Correspondence: ; Tel.: +1-402-559-8690
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18
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Swain Y, Muelken P, Skansberg A, Lanzdorf D, Haave Z, LeSage MG, Gewirtz JC, Harris AC. Higher anhedonia during withdrawal from initial opioid exposure is protective against subsequent opioid self-administration in rats. Psychopharmacology (Berl) 2020; 237:2279-2291. [PMID: 32388620 PMCID: PMC7354901 DOI: 10.1007/s00213-020-05532-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
RATIONALE Understanding factors contributing to individual differences in vulnerability to opioid addiction is essential for developing more effective preventions and treatments, yet few reliable behavioral predictors of subsequent opioid self-administration have been identified in rodents. Sensitivity to the acute effects of initial drug exposure predicts later addiction vulnerability in both humans and animals, but the relationship between sensitivity to withdrawal from initial drug exposure and later drug use vulnerability is unclear. OBJECTIVE The goal of the current study was to evaluate whether the degree of anhedonia experienced during withdrawal from early opioid exposure predicts subsequent vulnerability to opioid self-administration. METHODS Rats were first tested for withdrawal sensitivity following acute injections of morphine (i.e., "acute dependence"), measured as elevations in intracranial self-stimulation (ICSS) thresholds (anhedonia-like behavior) during naloxone-precipitated and spontaneous withdrawal. Rats were then tested for addiction-like behavior using various measures of i.v. morphine self-administration (MSA) including acquisition, demand, extinction, and reinstatement induced by morphine, stress, and/or drug-associated cues. RESULTS Greater naloxone-precipitated withdrawal across repeated morphine injections and greater peak spontaneous withdrawal severity following a single morphine injection were associated with lower addiction-like behavior on multiple MSA measures. Withdrawal-induced anhedonia predicted a wider range of MSA measures than did any individual measure of MSA itself. CONCLUSIONS Our data establish WIA as one of the first behavioral measures to predict individual differences in opioid SA in rodents. This model promises to be useful for furthering our understanding of behavioral and neurobiological mechanisms underlying vulnerability to opioid addiction.
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Affiliation(s)
- Yayi Swain
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Psychology
| | | | - Annika Skansberg
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Psychology
| | - Danielle Lanzdorf
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Psychology
| | - Zachary Haave
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Neuroscience
| | - Mark G. LeSage
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Psychology,,University of Minnesota Department of Medicine
| | - Jonathan C. Gewirtz
- University of Minnesota Department of Psychology,,University of Minnesota Department of Neuroscience
| | - Andrew C. Harris
- Hennepin Healthcare Research Institute,,University of Minnesota Department of Psychology,,University of Minnesota Department of Medicine
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19
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Strickland JC, Lacy RT. Behavioral economic demand as a unifying language for addiction science: Promoting collaboration and integration of animal and human models. Exp Clin Psychopharmacol 2020; 28:404-416. [PMID: 32105136 PMCID: PMC7390687 DOI: 10.1037/pha0000358] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The intersection of pharmacological, psychological, and economic theory within behavioral economics has helped advance an understanding of substance use disorder. A notable contribution of this approach is the conceptualization of reinforcement from a behavioral economic demand perspective. Demand analyses provide a multidimensional view of reinforcement in which distinct behavioral mechanisms are measured that impact decision making and drug consumption. This review describes the state of research on behavioral economic demand as a common language for addiction science researchers across varied model systems and stages of a translational continuum. We first provide an overview of the theoretical concepts and procedures used to evaluate demand in animal and human models. The potential for demand to serve as a common language for diverse research groups in psychopharmacology and addiction science (e.g., those evaluating neurobehavioral outcomes, medications development, clinical practice) is then described. An overview is also provided of existing empirical studies that, while small in number, suggest good linguistic and conceptual overlap between animal and human demand models when studying biological, environmental, and pharmacological individual difference vulnerabilities underlying drug-taking behavior. Refinement of methodological procedures and incorporation of more nuanced environmental features should help improve correspondence between animal and human demand studies as well as clinical translation of such findings. Our hope is that this review and commentary ultimately serves as inspiration for new collaborative efforts involving behavioral economic demand between animal and human researchers who share a common goal of improving substance use treatment outcomes and broader psychological wellbeing. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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20
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Hempel BJ, Melkumyan M, Crissman ME, Winston CA, Madar J, Riley AL. Pre-conception exposure to THC fails to impact nicotine reward in adult offspring. Pharmacol Biochem Behav 2020; 197:173001. [PMID: 32710886 DOI: 10.1016/j.pbb.2020.173001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/19/2020] [Indexed: 01/04/2023]
Abstract
Exposure to environmental stimuli in one generation can produce altered behavioral and neurobiological phenotypes in descendants. Recent work has shown that parental exposure to cannabinoids alters the rewarding properties of other abused drugs in the subsequent generation. However, whether preconception Δ9-tetrahydrocannabinol (THC) administration modifies the affective properties of nicotine in offspring is unknown. To address this question, male and female rats (F0) received THC (0 or 1.5 mg/kg) throughout the adolescent window and were bred on PND 65. In Experiment 1, adult F1-THC and F1-Veh progeny (males and females) underwent nicotine locomotor sensitization procedures during which nicotine (0 or 0.4 mg/kg) was administered every other day for five exposures, and locomotor activity was recorded on each exposure followed by a final nicotine challenge. There was no cross-generational effect of THC on nicotine locomotor sensitization, although acute exposure to nicotine produced greater activity in females relative to males independent of THC history. In Experiment 2, adult F1-THC and F1-Veh progeny (males and females) were implanted with jugular catheters and trained to self-administer nicotine (0.03 mg/kg/infusion). Following acquisition, all subjects were allowed to self-administer nicotine on a number of reinforcement schedules, e.g., FR2, FR5 and PR, followed by dose response and extinction procedures. Across all indices, F1-THC and F1-Veh subjects displayed similar IVSA of nicotine with no sex differences. The fact that there was no evidence of cross-generational effects of THC on nicotine suggests that such effects are drug-specific.
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Affiliation(s)
- Briana J Hempel
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA.
| | - Mariam Melkumyan
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA
| | - Madeline E Crissman
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA
| | - Chloe A Winston
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA
| | - Jacob Madar
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA
| | - Anthony L Riley
- Psychopharmacology Laboratory, Center for Behavioral Neuroscience, American University, 4400 Massachusetts Ave NW, Washington, D.C. 20016, USA.
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21
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Chellian R, Behnood-Rod A, Wilson R, Kamble SH, Sharma A, McCurdy CR, Bruijnzeel AW. Adolescent nicotine and tobacco smoke exposure enhances nicotine self-administration in female rats. Neuropharmacology 2020; 176:108243. [PMID: 32702403 DOI: 10.1016/j.neuropharm.2020.108243] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/24/2020] [Accepted: 07/13/2020] [Indexed: 12/30/2022]
Abstract
Most people start experimenting with tobacco products or e-cigarettes in early adolescence and become habitual smokers in late adolescence or adulthood. These studies investigated if exposure to tobacco smoke or nicotine during early and mid-adolescence affects nicotine intake in late adolescence and early adulthood. Male and female rats were exposed to tobacco smoke from low- and high-nicotine SPECTRUM cigarettes or nicotine (0.3 mg/kg, twice a day) from postnatal day (P) 24-42. The self-administration sessions started at P55. The rats self-administered nicotine for 14-15 days under a fixed-ratio 1 schedule, and on the first day, the maximum number of infusions was twenty. Exposure to smoke from high, but not low, nicotine cigarettes during adolescence increased nicotine self-administration in female but not male rats. Adolescent treatment with nicotine facilitated nicotine self-administration. On the first day of nicotine self-administration, nicotine-treated rats reached the maximum number of infusions before the saline-treated control rats. Nicotine intake was also higher in the nicotine-treated female rats than in the saline-treated females. There was no sex difference in nicotine intake in controls when the data from the studies were combined. Smoke exposure led to a dose-dependent increase in plasma nicotine and cotinine levels in adolescent rats. Exposure to smoke from high-nicotine cigarettes and 0.3 mg/kg of nicotine led to plasma nicotine and cotinine levels that are similar to those in tobacco users. These findings indicate that in females, but not males, exposure to nicotine during adolescence may facilitate smoking and e-cigarette use later in life.
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Affiliation(s)
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Shyam H Kamble
- Department of Pharmaceutics, University of Florida, Gainesville, FL, USA; Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, FL, USA
| | - Abhisheak Sharma
- Department of Pharmaceutics, University of Florida, Gainesville, FL, USA; Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, FL, USA
| | - Christopher R McCurdy
- Translational Drug Development Core, Clinical and Translational Sciences Institute, University of Florida, Gainesville, FL, USA; Department of Medicinal Chemistry, University of Florida, Gainesville, FL, USA
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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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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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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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Goenaga J, Powell GL, Leyrer-Jackson JM, Piña J, Phan S, Prakapenka AV, Koebele SV, Namba MD, McClure EA, Bimonte-Nelson HA, Gipson CD. N-acetylcysteine yields sex-specific efficacy for cue-induced reinstatement of nicotine seeking. Addict Biol 2020; 25:e12711. [PMID: 30734439 PMCID: PMC6685767 DOI: 10.1111/adb.12711] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/05/2018] [Accepted: 11/29/2018] [Indexed: 12/28/2022]
Abstract
Women report greater craving during certain phases of the menstrual cycle. As well, research indicates that pharmacotherapies for smoking may be less efficacious in women compared with men, which may be due to interactions with natural fluctuations in ovarian hormone levels. N-Acetylcysteine (NAC) is a glutamatergic compound that has shown some efficacy in treating substance use disorders and aids in the prevention of relapse. However, it is unclear whether NAC has sex-specific effectiveness for nicotine relapse treatment. Given that NAC has shown promise to reduce nicotine reinstatement in preclinical models using male rats, the exploration of potential sex differences in the efficacy of NAC is warranted. Using a rat model, we first investigated the ability of NAC treatment (100 mg/kg, ip) during nicotine withdrawal with extinction training to reduce cue-induced nicotine seeking in male and female rats. Next, we assessed whether NAC's effects were estrous cycle-dependent for female rats. Results show that following NAC treatment during extinction, reinstatement of nicotine seeking was significantly decreased in males but not females, indicating a sex-specific effect of NAC. Furthermore, for females, both vehicle- and NAC-treated groups significantly reinstated nicotine-seeking behavior compared with extinction, regardless of estrous cycle phase. These results suggest that NAC is inefficacious in reducing nicotine relapse in females regardless of estrous cycle phase at the dose evaluated here. These collective findings could have important clinical implications for use and efficacy of NAC as a pharmacotherapy for freely cycling women smokers.
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Affiliation(s)
| | | | | | - Jose Piña
- Department of Psychology, Arizona State University, Tempe, AZ
| | - Sandy Phan
- Department of Psychology, Arizona State University, Tempe, AZ
| | - Alesia V. Prakapenka
- Department of Psychology, Arizona State University, Tempe, AZ
- Arizona Alzheimer’s Consortium, Phoenix, AZ
| | - Stephanie V. Koebele
- Department of Psychology, Arizona State University, Tempe, AZ
- Arizona Alzheimer’s Consortium, Phoenix, AZ
| | - Mark D. Namba
- Department of Psychology, Arizona State University, Tempe, AZ
| | - Erin A. McClure
- Department of Psychiatry, Medical University of South Carolina, Charleston, SC
| | - Heather A. Bimonte-Nelson
- Department of Psychology, Arizona State University, Tempe, AZ
- Arizona Alzheimer’s Consortium, Phoenix, AZ
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26
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Lacy RT, Austin BP, Strickland JC. The influence of sex and estrous cyclicity on cocaine and remifentanil demand in rats. Addict Biol 2020; 25:e12716. [PMID: 30779409 PMCID: PMC6916383 DOI: 10.1111/adb.12716] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 01/03/2019] [Accepted: 01/06/2019] [Indexed: 12/25/2022]
Abstract
The application of behavioral economic demand theory in addiction science has proved useful for evaluating individual characteristics underlying abuse liability. Two factors that have received comparably little attention within this literature are sex and gonadal hormones. We determined cocaine and remifentanil demand in male and female rats using a within‐session procedure. Cocaine and remifentanil demand were evaluated for 15 consecutive days using a balanced, crossover design that randomized drug order. This design allowed for the evaluation of temporal and exposure effects on two independent dimensions of demand, unconstrained demand (Q0) and demand elasticity (α). Estrous cyclicity was tracked to determine the contribution of phase to demand. No overall sex differences were observed. Increased unconstrained demand for cocaine and remifentanil was observed in females during periods in which estrogen was high (eg, estrus phase). Unconstrained remifentanil demand escalated over the 15‐day testing period, but escalation was not observed for cocaine or for demand elasticity. A significant exposure effect was also observed in which greater prior remifentanil intake increased unconstrained cocaine demand and reduced cocaine demand elasticity. These effects were directionally specific as no significant effects of prior cocaine exposure were observed on remifentanil demand measures. These data suggest that unconstrained demand and demand elasticity do not differ between male and female subjects; however, that unconstrained demand is associated with estrous cyclicity. These findings also suggest that opioid exposure enhances subsequent demand for psychomotor stimulants, which may be important when considering recent increases in nonmedical prescription opioid use in the United States.
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Affiliation(s)
- Ryan T. Lacy
- Department of Psychology Franklin & Marshall College Lancaster PA USA
| | - Bridget P. Austin
- Department of Psychology Franklin & Marshall College Lancaster PA USA
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27
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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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28
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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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29
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Ho YY, Nhu Vo T, Chu H, LeSage MG, Luo X, Le CT. A Bayesian hierarchical model for demand curve analysis. Stat Methods Med Res 2018; 27:2401-2412. [PMID: 29984638 DOI: 10.1177/0962280216680651] [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] [Indexed: 11/15/2022]
Abstract
Drug self-administration experiments are a frequently used approach to assess the abuse liability and reinforcing property of a compound. It has been used to assess the abuse liabilities of various substances such as psychomotor stimulants and hallucinogens, food, nicotine, and alcohol. The demand curve generated from a self-administration study describes how demand of a drug or non-drug reinforcer varies as a function of price. With the approval of the 2009 Family Smoking Prevention and Tobacco Control Act, demand curve analysis provides crucial evidence to inform the US Food and Drug Administration's policy on tobacco regulation because it produces several important quantitative measurements to assess the reinforcing strength of nicotine. The conventional approach popularly used to analyze the demand curve data is individual-specific non-linear least square regression. The non-linear least square approach sets out to minimize the residual sum of squares for each subject in the dataset; however, this one-subject-at-a-time approach does not allow for the estimation of between- and within-subject variability in a unified model framework. In this paper, we review the existing approaches to analyze the demand curve data, non-linear least square regression, and the mixed effects regression and propose a new Bayesian hierarchical model. We conduct simulation analyses to compare the performance of these three approaches and illustrate the proposed approaches in a case study of nicotine self-administration in rats. We present simulation results and discuss the benefits of using the proposed approaches.
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Affiliation(s)
- Yen-Yi Ho
- 1 Department of Statistics, College of Arts and Sciences, University of South Carolina, Columbia, SC, USA
| | - Tien Nhu Vo
- 2 Division of Epidemiology, School of Public Health, University of Minnesota, MN, USA
| | - Haitao Chu
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, MN, USA
| | - Mark G LeSage
- 4 Division of Clinical Pharmacology and Toxicology, Department of Medicine, University of Minnesota, MN, USA
| | - Xianghua Luo
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, MN, USA.,5 Masonic Cancer Center, University of Minnesota, MN, USA
| | - Chap T Le
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, MN, USA.,5 Masonic Cancer Center, University of Minnesota, MN, USA
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30
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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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31
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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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32
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Ho YY, Nhu Vo T, Chu H, Luo X, Le CT. A Bayesian hierarchical model for demand curve analysis. Stat Methods Med Res 2018; 27:2038-2049. [PMID: 29846147 DOI: 10.1177/0962280216673675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Drug self-administration experiments are a frequently used approach to assessing the abuse liability and reinforcing property of a compound. It has been used to assess the abuse liabilities of various substances such as psychomotor stimulants and hallucinogens, food, nicotine, and alcohol. The demand curve generated from a self-administration study describes how demand of a drug or non-drug reinforcer varies as a function of price. With the approval of the 2009 Family Smoking Prevention and Tobacco Control Act, demand curve analysis provides crucial evidence to inform the US Food and Drug Administration's policy on tobacco regulation, because it produces several important quantitative measurements to assess the reinforcing strength of nicotine. The conventional approach popularly used to analyze the demand curve data is individual-specific non-linear least square regression. The non-linear least square approach sets out to minimize the residual sum of squares for each subject in the dataset; however, this one-subject-at-a-time approach does not allow for the estimation of between- and within-subject variability in a unified model framework. In this paper, we review the existing approaches to analyze the demand curve data, non-linear least square regression, and the mixed effects regression and propose a new Bayesian hierarchical model. We conduct simulation analyses to compare the performance of these three approaches and illustrate the proposed approaches in a case study of nicotine self-administration in rats. We present simulation results and discuss the benefits of using the proposed approaches.
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Affiliation(s)
- Yen-Yi Ho
- 1 Department of Statistics, College of Arts and Sciences, University of South Carolina, South Carolina, SC, USA
| | - Tien Nhu Vo
- 2 Division of Epidemiology, School of Public Health, University of Minnesota, Minnesota, MN, USA
| | - Haitao Chu
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, Minnesota, MN, USA
| | - Xianghua Luo
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, Minnesota, MN, USA.,4 Masonic Cancer Center, University of Minnesota, Minnesota, MN, USA
| | - Chap T Le
- 3 Division of Biostatistics, School of Public Health, University of Minnesota, Minnesota, MN, USA.,4 Masonic Cancer Center, University of Minnesota, Minnesota, MN, USA
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33
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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: 15] [Impact Index Per Article: 2.5] [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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34
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Thompson MF, Poirier GL, Dávila-García MI, Huang W, Tam K, Robidoux M, Dubuke ML, Shaffer SA, Colon-Perez L, Febo M, DiFranza JR, King JA. Menthol enhances nicotine-induced locomotor sensitization and in vivo functional connectivity in adolescence. J Psychopharmacol 2018; 32:332-343. [PMID: 28747086 DOI: 10.1177/0269881117719265] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mentholated cigarettes capture a quarter of the US market, and are disproportionately smoked by adolescents. Menthol allosterically modulates nicotinic acetylcholine receptor function, but its effects on the brain and nicotine addiction are unclear. To determine if menthol is psychoactive, we assessed locomotor sensitization and brain functional connectivity. Adolescent male Sprague Dawley rats were administered nicotine (0.4 mg/kg) daily with or without menthol (0.05 mg/kg or 5.38 mg/kg) for nine days. Following each injection, distance traveled in an open field was recorded. One day after the sensitization experiment, functional connectivity was assessed in awake animals before and after drug administration using magnetic resonance imaging. Menthol (5.38 mg/kg) augmented nicotine-induced locomotor sensitization. Functional connectivity was compared in animals that had received nicotine with or without the 5.38 mg/kg dosage of menthol. Twenty-four hours into withdrawal after the last drug administration, increased functional connectivity was observed for ventral tegmental area and retrosplenial cortex with nicotine+menthol compared to nicotine-only exposure. Upon drug re-administration, the nicotine-only, but not the menthol groups, exhibited altered functional connectivity of the dorsal striatum with the amygdala. Menthol, when administered with nicotine, showed evidence of psychoactive properties by affecting brain activity and behavior compared to nicotine administration alone.
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Affiliation(s)
- Matthew F Thompson
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,2 Department of Biology, Clark University, Worcester, MA, USA
| | - Guillaume L Poirier
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Martha I Dávila-García
- 3 Department of Pharmacology, Howard University College of Medicine, Washington, DC, USA
| | - Wei Huang
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Kelly Tam
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Maxwell Robidoux
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA
| | - Michelle L Dubuke
- 4 Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,5 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, MA, USA
| | - Scott A Shaffer
- 4 Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,5 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, MA, USA
| | - Luis Colon-Perez
- 6 Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA
| | - Marcelo Febo
- 6 Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA
| | - Joseph R DiFranza
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,7 Department of Family Medicine and Community Health, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jean A King
- 1 Center for Comparative NeuroImaging, University of Massachusetts Medical School, Worcester, MA, USA.,8 Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA.,9 Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
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35
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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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Sex differences in nicotine intravenous self-administration: A meta-analytic review. Physiol Behav 2017; 203:42-50. [PMID: 29158125 DOI: 10.1016/j.physbeh.2017.11.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/04/2017] [Accepted: 11/12/2017] [Indexed: 11/22/2022]
Abstract
OBJECTIVE This report reflects a meta-analysis that systematically reviewed the literature on intravenous self-administration (IVSA) of nicotine in female and male rats. The goal was to determine if sex differences in nicotine IVSA exist, estimate the magnitude of the effect, and identify potential moderators of the relationship between sex differences and nicotine consumption. METHODS Extensive search procedures identified 20 studies that met the inclusion criteria of employing both female and male rats in nicotine IVSA procedures. The meta-analysis was conducted on effect size values that were calculated from mean total intake or nicotine deliveries using the Hedges' unbiased gu statistic. RESULTS A random effects analysis revealed that overall females self-administered more nicotine than males (weighted gu=0.18, 95% CI [0.003, 0.34]). Subsequent moderator variable analyses revealed that certain procedural conditions influenced the magnitude of sex differences in nicotine IVSA. Specifically, higher reinforcement requirements (>FR1) and extended-access sessions (23h) were associated with greater nicotine IVSA in females versus males. Females also displayed higher nicotine intake than males when the experiment included a light cue that signaled nicotine delivery. Sex differences were not influenced by the diurnal phase of testing, dose of nicotine, or prior operant training. CONCLUSION Overall, the results revealed that female rats display higher levels of nicotine IVSA than males, suggesting that the strong reinforcing effects of nicotine promote tobacco use in women.
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Cross SJ, Linker KE, Leslie FM. Sex-dependent effects of nicotine on the developing brain. J Neurosci Res 2017; 95:422-436. [PMID: 27870426 DOI: 10.1002/jnr.23878] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 07/08/2016] [Accepted: 07/14/2016] [Indexed: 02/06/2023]
Abstract
The use of tobacco products represents a major public health concern, especially among women. Epidemiological data have consistently demonstrated that women have less success quitting tobacco use and a higher risk for developing tobacco-related diseases. The deleterious effects of nicotine are not restricted to adulthood, as nicotinic acetylcholine receptors regulate critical aspects of neural development. However, the exact mechanisms underlying the particular sensitivity of women to develop tobacco dependence have not been well elucidated. In this mini-review, we show that gonadal hormone-mediated sexual differentiation of the brain may be an important determinant of sex differences in the effects of nicotine. We highlight direct interactions between sex steroid hormones and ligand-gated ion channels critical for brain maturation, and discuss the extended and profound sexual differentiation of the brain. We emphasize that nicotine exposure during the perinatal and adolescent periods interferes with normal sexual differentiation and can induce long-lasting, sex-dependent alterations in neuronal structure, cognitive and executive function, learning and memory, and reward processing. We stress important age and sex differences in nicotine's effects and emphasize the importance of including these factors in preclinical research that models tobacco dependence. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sarah J Cross
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
| | - Kay E Linker
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California
| | - Frances M Leslie
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California.,Department of Pharmacology, School of Medicine, University of California, Irvine, California
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Pogun S, Yararbas G, Nesil T, Kanit L. Sex differences in nicotine preference. J Neurosci Res 2017; 95:148-162. [PMID: 27870459 DOI: 10.1002/jnr.23858] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/29/2016] [Accepted: 07/11/2016] [Indexed: 01/01/2023]
Abstract
Smoking is the major cause of preventable deaths worldwide, and although there is a decline in overall smoking prevalence in developed countries, the decline in women is less pronounced than in men. Women become dependent faster and experience greater difficulties in quitting. Similar trends have been observed in animal models of nicotine/tobacco addiction. Individual differences in vulnerability to drug abuse are also observed in nicotine/tobacco addiction and point to the importance of sex differences. This Review, summarizes findings from three experimental approaches used to depict nicotine preference in animal models, intravenous and oral nicotine self-administration and nicotine-induced conditioned place preference. Nicotine preference is considered to be reflected in the animal's motivation to administer the drug (intravenously or orally) or to prefer an environment paired with the presence of the drug (conditioned place preference). These approaches all point to the importance of sex and age of the subjects; the preference of females and adolescents appear to be more pronounced than that of males and adults, respectively. A closer look at these factors will help us understand the mechanisms that underlie nicotine addiction and develop strategies to cope. Ignoring sex differences and reaching conclusions based only on studies using male subjects has resulted in erroneous generalizations in the past. Sex differences in nicotine preference have been clearly documented, and awareness on this aspect of nicotine dependence will significantly impact our success in translational research. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sakire Pogun
- Center for Brain Research, Ege University, Izmir, Turkey
| | - Gorkem Yararbas
- Institute on Drug Abuse, Toxicology and Pharmaceutical Science, Ege University, Izmir, Turkey
| | - Tanseli Nesil
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Lutfiye Kanit
- Center for Brain Research, Ege University, Izmir, Turkey.,Physiology Department, School of Medicine, Ege University, Izmir, Turkey
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Joukar S, Sheibani M. Combinatorial effect of nicotine and black tea on heart rate variability: Useful or harmful? ACTA ACUST UNITED AC 2017; 37:44-48. [DOI: 10.1111/aap.12059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/15/2017] [Accepted: 07/19/2017] [Indexed: 12/12/2022]
Affiliation(s)
- S. Joukar
- Physiology Research Center; Institute of Basic and Clinical Physiology Sciences; Kerman University of Medical Sciences; Kerman Iran
- Cardiovascular Research Center; Institute of Basic and Clinical Physiology Sciences; Kerman University of Medical Science; Kerman Iran
- Department of Physiology and Pharmacology; Medical School; Kerman University of Medical Sciences; Kerman Iran
| | - M. Sheibani
- Cardiovascular Research Center; Institute of Basic and Clinical Physiology Sciences; Kerman University of Medical Science; Kerman Iran
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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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41
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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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42
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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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44
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Jensen KP, DeVito EE, Valentine G, Gueorguieva R, Sofuoglu M. Intravenous Nicotine Self-Administration in Smokers: Dose-Response Function and Sex Differences. Neuropsychopharmacology 2016; 41:2034-40. [PMID: 26717881 PMCID: PMC4908640 DOI: 10.1038/npp.2015.373] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/03/2015] [Accepted: 12/05/2015] [Indexed: 01/26/2023]
Abstract
Sex differences in the sensitivity to nicotine may influence vulnerability to tobacco dependence. The goal of this study was to investigate the dose-response function for the reinforcing and subjective effects of intravenous nicotine in male and female smokers. Tobacco-dependent subjects (12 male and 14 female) participated in four experimental sessions in which they received sample infusions of saline and nicotine (0.1, 0.2, 0.3, or 0.4 mg doses) in a randomized double-blind crossover design. During each session, subjects first received the sample infusions, and heart rate (HR), blood pressure, and subjective stimulatory, pleasurable and aversive responses were monitored. Immediately following the sample infusions, subjects self-administered either nicotine or saline in six double-blind forced-choice trials. A sex by dose interaction was observed in the nicotine choice paradigm. Nicotine self-administration rate was negatively correlated with nicotine dose in males (males displayed choice preference for low doses of nicotine over high doses of nicotine), but no significant relationship between dose and choice preference was evident in females. Relative to placebo, sample doses of nicotine increased heart rate and blood pressure, and induced stimulatory, pleasurable, and aversive subjective effects. Diastolic blood pressure increased dose dependently in males, but not in females. These findings, which demonstrate sex differences in nicotine self-administration for doses that are near to the reinforcement threshold, suggest that male and female smokers may respond differently to the changes in nicotine doses available for self-administration.
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Affiliation(s)
- Kevin P Jensen
- Department of Psychiatry, School of Medicine, Yale University, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Elise E DeVito
- Department of Psychiatry, School of Medicine, Yale University, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Gerald Valentine
- Department of Psychiatry, School of Medicine, Yale University, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Ralitza Gueorguieva
- Department of Biostatistics, Yale University School of Public Health and School of Medicine, New Haven, CT, USA
| | - Mehmet Sofuoglu
- Department of Psychiatry, School of Medicine, Yale University, VA Connecticut Healthcare System, West Haven, CT, USA,Department of Psychiatry, School of Medicine, Yale University, VA Connecticut Healthcare System, 950 Campbell Ave., Bldg. 36/116A4, West Haven, CT 06516, USA, Tel: 203 937 4809, Fax: 203 937 3478, E-mail:
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Pittenger ST, Swalve N, Chou S, Smith MD, Hoonakker AJ, Pudiak CM, Fleckenstein AE, Hanson GR, Bevins RA. Sex differences in neurotensin and substance P following nicotine self-administration in rats. Synapse 2016; 70:336-46. [PMID: 27074301 DOI: 10.1002/syn.21907] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/21/2016] [Accepted: 04/08/2016] [Indexed: 02/02/2023]
Abstract
Investigator-administered nicotine alters neurotensin and substance P levels in Sprague-Dawley rats. This finding suggested a role of the dopamine-related endogenous neuropeptides in nicotine addiction. We sought to extend this observation by determining the responses of neurotensin and substance P systems (assessed using radioimmunoassay) in male and female rats following nicotine self-administration (SA). Male and female Sprague-Dawley were trained to self-administer nicotine, or receive saline infusions yoked to a nicotine-administering rat during daily sessions (1-h; 21 days). Brains were extracted 3 h after the last SA session. Nicotine SA increased tissue levels of neurotensin in the males in the anterior and posterior caudate, globus pallidus, frontal cortex, nucleus accumbens core and shell, and ventral tegmental area. Nicotine SA also increased tissue levels of neurotensin in the females in the anterior caudate, globus pallidus, nucleus accumbens core and shell, but not in the posterior caudate, frontal cortex, or ventral tegmental area. There were fewer sex differences observed in the substance P systems. Nicotine SA increased tissue levels of substance P in both the males and females in the posterior caudate, globus pallidus, frontal cortex, nucleus accumbens shell, and ventral tegmental area. A sex difference was observed in the nucleus accumbens core, where nicotine SA increased tissue levels of substance P in the males, yet decreased levels in the females. The regulation of neuropeptides following nicotine SA may play a role in the susceptibility to nicotine dependence in females and males. Synapse 70:336-346, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Steven T Pittenger
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, Nebraska, 68588-0308
| | - Natashia Swalve
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, Nebraska, 68588-0308
| | - Shinnyi Chou
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, Nebraska, 68588-0308
| | - Misty D Smith
- School of Dentistry, University of Utah, 530 so. Wakara Way, Salt Lake City, Utah, 84108.,Department of Pharmacology and Toxicology, University of Utah, Skaggs Hall, Salt Lake City, Utah, 84112
| | - Amanda J Hoonakker
- School of Dentistry, University of Utah, 530 so. Wakara Way, Salt Lake City, Utah, 84108
| | - Cindy M Pudiak
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, Nebraska, 68588-0308
| | - Annette E Fleckenstein
- School of Dentistry, University of Utah, 530 so. Wakara Way, Salt Lake City, Utah, 84108
| | - Glen R Hanson
- School of Dentistry, University of Utah, 530 so. Wakara Way, Salt Lake City, Utah, 84108.,Department of Pharmacology and Toxicology, University of Utah, Skaggs Hall, Salt Lake City, Utah, 84112
| | - Rick A Bevins
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, Nebraska, 68588-0308
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Swalve N, Smethells JR, Carroll ME. Sex differences in attenuation of nicotine reinstatement after individual and combined treatments of progesterone and varenicline. Behav Brain Res 2016; 308:46-52. [PMID: 27091301 DOI: 10.1016/j.bbr.2016.04.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 01/08/2023]
Abstract
Tobacco use is the largest cause of preventable mortality in the western world. Even after treatment, relapse rates for tobacco are high, and more effective pharmacological treatments are needed. Progesterone (PRO), a female hormone used in contraceptives, reduces stimulant use but its effects on tobacco addiction are unknown. Varenicline (VAR) is a commonly used medication that reduces tobacco use. The present study examined sex differences in the individual vs. combined effects of PRO and VAR on reinstatement of nicotine-seeking behavior in a rat model of relapse. Adult female and male Wistar rats self-administered nicotine (NIC, 0.03mg/kg/infusion) for 14days followed by 21days of extinction when no cues or drug were present. Rats were then divided into 4 treatment groups: control (VEH+SAL), PRO alone (PRO+SAL), VAR alone (VEH+VAR) and the combination (PRO+VAR). Reinstatement of nicotine-seeking behavior induced by priming injections of NIC or caffeine (CAF), presentation of cues (CUES), and the combination of drugs and cues (e.g. NIC+CUES, CAF+CUES) were tested after extinction. Male and female rats did not differ in self-administration of nicotine or extinction responding, and both showed elevated levels of responding to the CAF+CUES condition. However, males, but not females, reinstated active lever-pressing to the NIC+CUES condition, and that was attenuated by both VAR and VAR+PRO treatment. Thus, males were more sensitive to NIC+CUE-induced reinstatement than females, and VAR alone and VAR combined with PRO effectively reduced nicotine relapse.
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Affiliation(s)
- Natashia Swalve
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - John R Smethells
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Marilyn E Carroll
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, 55455, USA
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Estradiol promotes the rewarding effects of nicotine in female rats. Behav Brain Res 2016; 307:258-63. [PMID: 27059334 DOI: 10.1016/j.bbr.2016.04.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 03/26/2016] [Accepted: 04/04/2016] [Indexed: 02/02/2023]
Abstract
It is presently unclear whether ovarian hormones, such as estradiol (E2), promote the rewarding effects of nicotine in females. Thus, we compared extended access to nicotine intravenous self-administration (IVSA) in intact male, intact female, and OVX female rats (Study 1) as well as OVX females that received vehicle or E2 supplementation (Study 2). The E2 supplementation procedure involved a 4-day injection regimen involving 2 days of vehicle and 2 days of E2 administration. Two doses of E2 (25 or 250μg) were assessed in separate groups of OVX females in order to examine the dose-dependent effects of this hormone on the rewarding effects of nicotine. The rats were given 23-hour access to nicotine IVSA using an escalating dose regimen (0.015, 0.03, and 0.06mg/kg/0.1mL). Each dose was self-administered for 4 days with 3 intervening days of nicotine abstinence. The results revealed that intact females displayed higher levels of nicotine intake as compared to males. Also, intact females displayed higher levels of nicotine intake versus OVX females. Lastly, our results revealed that OVX rats that received E2 supplementation displayed a dose-dependent increase in nicotine intake as compared to OVX rats that received vehicle. Together, our results suggest that the rewarding effects of nicotine are enhanced in female rats via the presence of the ovarian hormone, E2.
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Sex differences in the acquisition and maintenance of cocaine and nicotine self-administration in rats. Psychopharmacology (Berl) 2016; 233:1005-13. [PMID: 26685990 PMCID: PMC4761341 DOI: 10.1007/s00213-015-4183-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 12/03/2015] [Indexed: 10/22/2022]
Abstract
RATIONALE Consistent sex differences are observed in human drug addiction, with females often exceeding males on drug intake. However, there is still a need for animal models for some aspects of addiction such as acquisition of drug self-administration and the subsequent development of drug-seeking. OBJECTIVES The present study examined sex differences in the acquisition and maintenance of self-administration of two widely used stimulants, cocaine and nicotine. METHODS Male and female rats self-administered cocaine (0.4 mg/kg/infusion) or nicotine (0.03 mg/kg/infusion) daily under a fixed-ratio 1 (FR 1) schedule until acquisition criteria were met (maximum of 30 sessions). The self-administration criterion for cocaine was ≥20 infusions in a 2-h session and ≥5 infusions in a 1-h session for nicotine. Sex differences were assessed by examining the percentage of rats that met acquisition criteria, the number of sessions to meet criteria, and the number of infusions earned during the maintenance phase. RESULTS A significantly higher percentage of male rats acquired both cocaine and nicotine self-administration than females, and males met acquisition criteria in fewer sessions. However, after criteria were met, females self-administered more cocaine than males during the first 5 days of maintenance. There were no sex differences in nicotine infusions post-acquisition. CONCLUSIONS Differences in acquisition amongst sexes can reveal factors that are integral to initiation of drug use, an often overlooked phase of drug addiction.
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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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Combes RD, Balls M. A critical assessment of the scientific basis, and implementation, of regulations for the safety assessment and marketing of innovative tobacco-related products. Altern Lab Anim 2015; 43:251-90. [PMID: 26375889 DOI: 10.1177/026119291504300406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Our scientific, logistical, ethical and animal welfare-related concerns about the latest US Food and Drug Administration (FDA) regulations for existing and so-called 'new' tobacco products, aimed at reducing harmful exposures, are explained. Such claims for sales in the USA now have to be based on a wide range of information, a key part of which will increasingly be data on safety and risk. One of the pathways to achieve marketing authorisation is to demonstrate substantial equivalence (SE) with benchmark products, called predicates. However, the regulations are insufficiently transparent with regard to: a) a rationale for the cut-off date for 'old' and 'new' products, and for exempting the former from regulation; b) the scientific validity and operation of SE; c) options for product labelling to circumvent SE; d) the experimental data required to support, and criteria to judge, a claim; and e) a strategy for risk assessment/management. Scientific problems related to the traditional animal methods used in respiratory disease and inhalation toxicology, and the use of quantitative comparators of toxicity, such as the No Observed Adverse Effect Level, are discussed. We review the advantages of relevant in vitro, mechanism-based, target tissue-oriented technologies, which an advisory report of the Institute of Medicine of the US National Academy of Sciences largely overlooked. These benefits include: a) the availability, for every major site in the respiratory tract, of organotypic human cell-based tissue culture systems, many of which are already being used by the industry; b) the accurate determination of concentrations of test materials received by target cells; c) methods for exposure to particulate and vapour phases of smoke, separately or combined; d) the ability to study tissue-specific biotransformation; and e) the use of modern, human-focused methodologies, unaffected by species differences. How data extrapolation, for risk assessment, from tissue culture to the whole animal, could be addressed, is also discussed. A cost (to animal welfare)-benefit (to society, including industry and consumers) analysis was conducted, taking into account the above information; the potential for animal suffering; the extensive data already available; the existence of other, less hazardous forms of nicotine delivery; the fact that much data will be generated solely for benchmarking; and that many smokers (especially nicotine-dependents) ignore health warnings. It is concluded that, in common with policies of several tobacco companies and countries, the use of laboratory animals for tobacco testing is very difficult, if not impossible, to justify. Instead, we propose and argue for an integrated testing scheme, starting with extensive chemical analysis of the ingredients and by-products associated with the use of tobacco products and their toxicity, followed by use of in vitro systems and early clinical studies (involving specific biomarkers) with weight-of-evidence assessments at each stage. Appropriate adjustment factors could be developed to enable concentration-response data obtained in vitro, with the other information generated by the strategy, to enable the FDA to meet its objectives. It is hoped that our intentionally provocative ideas will stimulate further debate on this contentious area of regulatory testing and public safety.
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