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Walker NB, Tucker BR, Thomas LN, Tapp AE, Drenan DR, Drenan RM. Expression of sensitized β2 nAChR subunits in VTA neurons enhances intravenous nicotine self-administration in male rats. Neuropharmacology 2024; 261:110161. [PMID: 39299573 PMCID: PMC11486559 DOI: 10.1016/j.neuropharm.2024.110161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Revised: 09/12/2024] [Accepted: 09/13/2024] [Indexed: 09/22/2024]
Abstract
Ventral tegmental area (VTA) nicotinic acetylcholine receptors (nAChRs) are important for nicotine reinforcement. To determine whether and to what extent these receptors are sufficient for nicotine reinforcement, we expressed β2Leu9'Ser (i.e. sensitized) nAChR subunits in the VTA of adult male rats and assessed the nicotine dose-response relationship in intravenous self-administration (SA). β2Leu9'Ser rats self-administered nicotine doses 50-100 fold lower than the lowest doses that control rats would respond for. Expression of WT β2 subunits confirmed that this enhanced sensitivity to nicotine was due to the Leu9'Ser mutation in β2. Higher unit doses were associated with strong escalation in β2Leu9'Ser rats over 17 fixed ratio sessions. Escalation was minimal or absent in control rats at the same unit doses. In progressive ratio SA, β2Leu9'Ser rats exhibited higher breakpoints than control rats when the nicotine unit dose was 1.5 μg/kg/inf or higher. In intermittent access SA, β2Leu9'Ser rats exhibited response patterns very similar to control rats. By adding nicotine dose-response data, progressive ratio assays, and intermittent access results that rule out stereotypy, these data significantly extend our previous finding that nicotine activation of the mesolimbic dopamine pathway is sufficient for nicotine reinforcement.
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Affiliation(s)
- Noah B Walker
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Brenton R Tucker
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Leanne N Thomas
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Andrew E Tapp
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Dylan R Drenan
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Ryan M Drenan
- Department of Translational Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
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Marusich JA, Palmatier MI. Development of a nicotine aerosol self-administration model in rats and the effects of e-liquid flavors. Behav Pharmacol 2023; 34:141-153. [PMID: 36752651 PMCID: PMC10006336 DOI: 10.1097/fbp.0000000000000717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Electronic nicotine delivery system (ENDS) use is maintained by the positive reinforcement associated with preferred flavors. These flavors become conditioned reinforcers through pairings with primary reinforcers. This study sought to extend prior research with intravenous nicotine self-administration and develop a more ecologically valid preclinical model of aerosol self-administration in rats that incorporated flavors paired with sucrose. Rats were first trained to respond for oral sucrose with or without raspberry flavor to establish the flavor as a conditioned reinforcer for some groups. Rats were then exposed to aerosol self-administration. All groups responded for raspberry-flavored aerosol with or without nicotine. Rats responded more for raspberry flavored sucrose than unflavored sucrose. Despite raspberry increasing responding for sucrose, the flavor did not function as a conditioned reinforcer during aerosol self-administration and did not increase responding for nicotine. Throughout the aerosol self-administration phase, most groups responded more on the active than inactive lever, and some groups increased their response when the fixed ratio value was increased. At the end of the study, rats in nicotine groups earned similar or fewer aerosol deliveries than rats in vehicle groups. Aerosolized nicotine did not function as a reinforcer in this study, whereas aerosolized raspberry flavor may have maintained self-administration. Further preclinical investigation is needed to articulate the impact of flavors on ENDS use and whether they offset some aversive effects of nicotine or maintain responding on their own. If flavors reduce some aversive effects of self-administered nicotine, then policies to regulate flavors in e-liquids are prudent.
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Affiliation(s)
- Julie A Marusich
- Center for Drug Discovery, RTI International, Research Triangle Park, NC
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3
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Sved AF, Caggiula AR, Donny EC. Elucidating the reinforcing effects of nicotine: a tribute to Nadia Chaudhri. Psychopharmacology (Berl) 2023; 240:417-430. [PMID: 36329195 PMCID: PMC11188050 DOI: 10.1007/s00213-022-06266-7] [Citation(s) in RCA: 2] [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: 08/31/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
Nadia Chaudhri worked with us as a graduate student in the Center for Neuroscience at the University of Pittsburgh from 1999 until she earned her PhD in 2005, a time that coincided with the discovery in our lab of the dual reinforcing actions of nicotine, a concept that she played an important role in shaping. The research that was described in her doctoral thesis is among the foundational pillars of the now well-accepted notion that nicotine acts as both a primary reinforcer and an amplifier of other reinforcer stimuli. This reinforcement-enhancing action of nicotine is robust and likely to be a powerful driver of nicotine use. Below, we discuss the evidence that these two actions of nicotine - primary reinforcement and reinforcement enhancement - are distinct and dissociable, a finding that Nadia was closely associated with. We go on to address two other topics that greatly interested Nadia during that time, the generalizability of the reinforcement-enhancing action of nicotine to multiple classes of reinforcing stimuli and potential sex differences in the dual reinforcing actions of nicotine. The research has greatly expanded since Nadia's involvement, but the core ideas that she helped to develop remain central to the concept of the dual reinforcing actions of nicotine and its importance for understanding the drivers of nicotine use.
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Affiliation(s)
- Alan F Sved
- Departments of Neuroscience, Psychiatry and Psychology and the Center for Neuroscience, University of Pittsburgh, 210 Langley Hall, Pittsburgh, PA, 15260, USA.
| | - Anthony R Caggiula
- Departments of Psychology and Psychiatry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Eric C Donny
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157, USA
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Smith MA, Schmidt KT, Sharp JL, Pearson T, Davis AL, Gibson AN, Potter KM. Lack of evidence for positive reinforcing and prosocial effects of MDMA in pair-housed male and female rats. Eur J Pharmacol 2021; 913:174646. [PMID: 34800468 DOI: 10.1016/j.ejphar.2021.174646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA) is classified as an entactogen, producing feelings of emotional openness and relatedness. One unique feature of MDMA is that people tend to selectively take this drug in social and/or intimate situations. Although MDMA is recognized as having abuse liability, preclinical studies report that it has weak reinforcing effects in animals. The objective of this study was to characterize the positive reinforcing and prosocial effects of MDMA in a translational model of the social environment in which two rats have simultaneous and contingent access to MDMA in close physical proximity. To this end, MDMA self-administration was examined on both fixed and progressive ratio schedules of reinforcement in six groups of rats: (1) isolated males, (2) isolated females, (3) male-male dyads, (4) female-female dyads, (5) male-female dyads, and (6) female-male dyads. For pair-housed rats, data from both rats were analyzed. Next, social preferences were examined in a partner preference test. MDMA failed to produce positive reinforcing effects under all conditions examined. Across a 30-fold dose range (0.01-1.0 mg/kg/infusion), MDMA did not maintain higher responding than saline on both schedules of reinforcement and in all groups tested. In partner preference tests, a history of shared exposure to MDMA did not establish a social preference, and acute administration of MDMA failed to establish a preference for another MDMA-treated rat. These data suggest that social contact does not increase the positive reinforcing effects of MDMA in rats, and that neither contingent nor noncontingent MDMA administration establishes a social preference in rats.
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Affiliation(s)
- Mark A Smith
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA.
| | - Karl T Schmidt
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
| | - Jessica L Sharp
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
| | - Tallia Pearson
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
| | - Anna L Davis
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
| | - Abigail N Gibson
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
| | - Kenzie M Potter
- Department of Psychology and Program in Neuroscience, Davidson College, Davidson, NC, USA
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Spanos M, Xie X, Gras-Najjar J, White SC, Sombers LA. NMDA Receptor-Dependent Cholinergic Modulation of Mesolimbic Dopamine Cell Bodies: Neurochemical and Behavioral Studies. ACS Chem Neurosci 2019; 10:1497-1505. [PMID: 30412381 DOI: 10.1021/acschemneuro.8b00492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Substance abuse disorders are devastating, costly, and difficult to treat. Identifying the neurochemical mechanisms underlying reinforcement promises to provide critical information in the development of effective treatments. Several lines of evidence suggest that striatal dopamine (DA) release serves as a teaching signal in reinforcement learning, and that shifts in DA release from the primary reward to reward-predicting stimuli play a critical role in the self-administration of both natural and non-natural rewards. However, far less is known about the reinforcing effects of motivationally neutral sensory stimuli, or how these signals can facilitate self-administration behavior. Thus, we trained rats ( n = 7) to perform a visual stimulus-induced instrumental task, which involved lever pressing for activation of a stimulus light. We then microinfused vehicle (phosphate buffered saline), carbachol (acetylcholine receptor agonist), or carbachol in the presence of an N-methyl-d-aspartate (NMDA) receptor-specific drug (NMDA itself, or the antagonist, AP5) into the ventral tegmental area (VTA). This enabled us to directly evaluate how chemical modulation of dopamine cell bodies affects the instrumental behavior, as well as the nature of extracellular dopamine transients recorded in the nucleus accumbens shell (NAc shell) using fast-scan cyclic voltammetry (FSCV). Intra-VTA infusion of carbachol enhanced the magnitude and frequency of dopamine transients in the NAc shell and potentiated active lever responding without altering inactive lever responding, as compared to infusion of vehicle. Coinfusion of carbachol with AP5 abolished dopamine transients recorded in the NAc and attenuated active lever responding without altering inactive lever responding. Finally, coadministration of carbachol and NMDA into the VTA restored both lever pressing and dopaminergic signals recorded in the striatum. Together, these results suggest that acetylcholine and glutamate synergistically act at dopamine cells in the VTA to modulate VTA-NAc shell dopaminergic output, and this underlies motivation to lever press for a motivationally neutral visual stimulus.
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Affiliation(s)
- Marina Spanos
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Xiaohu Xie
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Julie Gras-Najjar
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Stephanie C. White
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Leslie A. Sombers
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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Randall PA, Fortino B, Huynh YW, Thompson BM, Larsen CE, Callen MP, Barrett ST, Murray JE, Bevins RA, Besheer J. Effects of nicotine conditioning history on alcohol and methamphetamine self-administration in rats. Pharmacol Biochem Behav 2019; 179:1-8. [PMID: 30664897 DOI: 10.1016/j.pbb.2019.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Smoking constitutes a significant public health risk. Alcohol and methamphetamine use disorders are also highly co-morbid with smoking, further increasing negative health outcomes. An important question in determining the underlying neurobiology of nicotine poly-drug use is understanding whether having a positive history with nicotine effects alters later drug-taking behavior. METHODS The current experiments sought to elucidate whether having an appetitive nicotine conditioning history would affect later alcohol or methamphetamine self-administration. Adult male and female Long-Evans rats were first trained on a discriminated goal-tracking task in which the interoceptive effects of nicotine predicted sucrose reinforcement. As a control, pseudo-conditioned groups were included that had equated nicotine and sucrose experience. Rats were then shifted to either alcohol self-administration or methamphetamine self-administration. RESULTS Nicotine conditioning history had no effect on acquisition or maintenance of alcohol self-administration in males or females. In contrast, an appetitive nicotine conditioning history decreased methamphetamine self-administration in female rats, but not males. CONCLUSIONS In female, but not male, rats, an appetitive conditioning history with nicotine decreases methamphetamine, but not alcohol, self-administration. This dissociation suggests that the effects may be due to a specific increase in the reinforcing value of methamphetamine. This may have implications for better understanding the progression of drug use from nicotine to methamphetamine.
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Affiliation(s)
- Patrick A Randall
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Brayden Fortino
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Y Wendy Huynh
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Brady M Thompson
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Christopher E Larsen
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Mackenzie P Callen
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Scott T Barrett
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Jennifer E Murray
- Department of Psychology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Rick A Bevins
- Department of Psychology, University of Nebraska at Lincoln, Lincoln, NE 68588, USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Curriculum in Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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How can we Improve on Modeling Nicotine Addiction to Develop Better Smoking Cessation Treatments? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:121-56. [PMID: 27055613 DOI: 10.1016/bs.irn.2016.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Clinically effective smoking cessation treatments are few in number, mainly varenicline, bupropion, and nicotine replacement therapy being prescribed by health organizations. Of the many compounds tested for smoking cessation, a good proportion fail in human trials despite positive findings in rodents. This chapter aims to cover the uses and some pit falls of current methodologies employed to discover clinical treatments in the laboratory. Complicating factors include the complex nature of genetics in tobacco smoking and the comorbidity associated with other psychiatric disorders, which has not been addressed fully in the rodent laboratory. This chapter reviews the evidence from intravenous nicotine self-administration studies and proposes modifications on how we can improve the validity of the animal models by incorporating clinically relevant factors considered to be critical in tobacco smoking. For example, choice procedures that incorporate alternative reinforcers, use of reinstatement models, and second-order schedules of reinforcement are proposed to have better scientific validity that may lead to better clinical outcomes. Furthermore, improved experimental methods will also improve our chances of discovering effective treatments that ultimately may mitigate the effects of tobacco smoking with regard to health worldwide.
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Schassburger RL, Pitzer EM, Smith TT, Rupprecht LE, Thiels E, Donny EC, Sved AF. Adolescent Rats Self-Administer Less Nicotine Than Adults at Low Doses. Nicotine Tob Res 2016; 18:1861-1868. [PMID: 26764255 DOI: 10.1093/ntr/ntw006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 01/04/2016] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Although nearly 90% of current smokers initiated tobacco use during adolescence, little is known about reinforcement by nicotine in adolescents. Researchers are currently investigating whether a potential public health policy setting a tobacco product standard with very low nicotine levels would improve public health, and it is essential to understand whether data generated in adults translates to adolescents, particularly as it relates to the threshold dose of nicotine required to support smoking. The present study compared self-administration of low doses of nicotine between adolescent and adult rats. METHODS Adolescent (postnatal day [P] 30) and adult (P90) male and female rats were allowed to nosepoke to receive intravenous infusions of nicotine (3-100 μg/kg/infusion) during 16 daily 1-hour sessions. RESULTS At 10 μg/kg/infusion nicotine, adolescent rats earned significantly fewer infusions than adults. When responding for 30 μg/kg/infusion nicotine, rats of both ages earned a similar number of infusions; however, there were subtle differences in the distribution of infusions across the 1-hour session. No sex differences were apparent in either age group at any dose. CONCLUSIONS These results demonstrate that adolescent rats are less sensitive than adults to the primary reinforcing effects of nicotine. However, at nicotine doses that support self-administration in both age groups, adolescent and adult rats do not differ in acquisition or number of infusions earned. These results suggest that reducing nicotine levels in cigarettes to a level that does not support smoking in adults may be sufficient to reduce the acquisition of smoking in adolescents. IMPLICATIONS The results of the present studies demonstrate that adolescent rats are less sensitive than adults to the primary reinforcing effects of nicotine. These results suggest that reducing nicotine levels in cigarettes to a level that does not support smoking in adults will be sufficient to reduce the acquisition of smoking in adolescents.
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Affiliation(s)
| | - Emily M Pitzer
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh , Pittsburgh, PA
| | - Tracy T Smith
- Department of Psychology, Dietrich School of Arts and Sciences, University of Pittsburgh , Pittsburgh, PA
| | | | - Edda Thiels
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA.,Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Eric C Donny
- Department of Psychology, Dietrich School of Arts and Sciences, University of Pittsburgh , Pittsburgh, PA
| | - Alan F Sved
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA.,Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Psychology, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA
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Neuroscience of learning and memory for addiction medicine: from habit formation to memory reconsolidation. PROGRESS IN BRAIN RESEARCH 2015; 223:91-113. [PMID: 26806773 DOI: 10.1016/bs.pbr.2015.07.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Identifying effective pharmacological treatments for addictive disorders has remained an elusive goal. Many different classes of drugs have shown some efficacy in preclinical models, but the number of effective clinical therapeutics has remained stubbornly low. The persistence of drug use and the high frequency of relapse is at least partly attributable to the enduring ability of environmental stimuli associated with drug use to maintain behavioral patterns of drug use and induce craving during abstinence. We propose that stimuli associated with drug use exert such powerful control over behavior through the development of abnormally strong memories, and their ability to initiate subconscious sequences of motor actions (habits) that promote uncontrolled drug use. In this chapter, we will review the evidence suggesting that drugs of abuse strengthen associations with cues in the environment and facilitate habit formation. We will also discuss potential mechanisms for disrupting memories associated with drug use to help improve treatments for addiction.
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Schassburger RL, Levin ME, Weaver MT, Palmatier MI, Caggiula AR, Donny EC, Sved AF. Differentiating the primary reinforcing and reinforcement-enhancing effects of varenicline. Psychopharmacology (Berl) 2015; 232:975-83. [PMID: 25209677 PMCID: PMC4326540 DOI: 10.1007/s00213-014-3732-x] [Citation(s) in RCA: 18] [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: 06/09/2014] [Accepted: 08/26/2014] [Indexed: 10/24/2022]
Abstract
RATIONALE Varenicline (VAR), a smoking cessation aid that is a partial agonist at nicotinic receptors, mimics the reinforcement-enhancing effects of nicotine. Varenicline, when accompanied by non-drug cues, is self-administered by rats, though it is unclear whether this results from varenicline acting as a primary reinforcer or a reinforcement enhancer of the cues. OBJECTIVES This study sought to disentangle these two potential actions. METHODS Rats were allowed to self-administer intravenous nicotine, saline, or varenicline during 1-h sessions in operant chambers equipped with two levers. Five groups had concurrent access to drug infusions and a moderately reinforcing visual stimulus (VS) for responding on separate levers. Meeting the reinforcement schedule on one lever was reinforced with VAR (0.01, 0.06, 0.1 mg/kg/infusion), nicotine (0.06 mg/kg/infusion), or saline, while meeting the same schedule on the other lever delivered the VS. Additional groups were reinforced for pressing a single "active" lever and received VAR paired with the VS, the VS with response-independent infusions of VAR, or VAR alone (0.1 mg/kg/infusion). RESULTS Rats readily responded for VAR paired with VS on a single lever. However, when VAR was the only reinforcer contingent on a response, rats did not respond more than for saline. CONCLUSIONS These findings show that VAR does not serve as a primary reinforcer in rats at doses that increase responding for non-drug reinforcers. These data are consistent with research showing that the primary reinforcing effects of VAR are weak, at best, and that the primary reinforcing and reinforcement-enhancing actions of nicotinic drugs are pharmacologically distinct.
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Affiliation(s)
- Rachel L. Schassburger
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA 15260, USA
| | - Melissa E. Levin
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
| | - Matthew T. Weaver
- Department of Psychology, Mercyhurst University, 103 Briggs Hall, Erie, PA 16546, USA
| | - Matthew I. Palmatier
- Department of Psychology, East Tennessee University, PO Box 70649, Johnson City, TN 37614, USA
| | - Anthony R. Caggiula
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
| | - Eric C. Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
| | - Alan F. Sved
- Department of Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, PA 15260, USA
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
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Nicotine enhances the expression of a sucrose or cocaine conditioned place preference in adult male rats. Pharmacol Biochem Behav 2014; 124:320-5. [PMID: 24967870 DOI: 10.1016/j.pbb.2014.06.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 05/20/2014] [Accepted: 06/15/2014] [Indexed: 12/30/2022]
Abstract
Nicotine has been shown to enhance the motivational properties of non-nicotine stimuli. This reinforcement-enhancing property of nicotine has the potential to promote the use of other illicit substances as well as maladaptive patterns of food intake. Therefore, the current study aimed to examine whether nicotine enhances preference for contexts paired with cocaine or sucrose utilizing a place conditioning procedure. Separate groups of adult male rats were administered sucrose or cocaine in one of two compartments of a standard CPP chamber on four consecutive days. Preference was then assessed following no injection, a single subcutaneous (s.c.) injection of nicotine, and a s.c. saline injection. The animals preferred the chamber paired with either sucrose or cocaine, as evident from an increased time spent in the paired chamber compared to baseline. Nicotine further increased the time spent in the sucrose- or cocaine-paired chamber, consistent with a reinforcement-enhancement effect. Previous results demonstrate an interaction between nicotine and intake of other drugs or food. The present findings provide an additional mechanism that may underlie these effects and which may have implications for drug dependence and obesity.
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12
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Palmatier MI, Lantz JE, O'Brien LC, Metz SP. Effects of nicotine on olfactogustatory incentives: preference, palatability, and operant choice tests. Nicotine Tob Res 2013; 15:1545-54. [PMID: 23430737 PMCID: PMC3741061 DOI: 10.1093/ntr/ntt016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 01/18/2013] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The use of additives in tobacco may capitalize on the incentive motivational properties of tastes and scents such as mint (menthol), vanilla, and strawberry. These incentives are intended to increase tobacco experimentation, but their salience may also be enhanced by the incentive amplifying effects of nicotine (NIC). The goal of the present studies was to investigate the potential interaction between the incentive amplifying effects of NIC and gustatory incentives. METHODS One of two discriminable tastes (grape or cherry Kool-Aid®; 0.05% wt/vol; unsweetened) was paired with sucrose (20% wt/vol; conditioned stimulus [CS+]) in deionized water, whereas the other taste (CS-) was presented in deionized water. Experiment 1 investigated the effects of NIC pretreatment on preference for the CS+ versus CS- in 2-bottle choice tests. Experiment 2 investigated the effects of NIC on palatability of the CS+ and CS- using orofacial taste reactions. Experiment 3 investigated the effects of NIC on reinforcement by the CS+ and CS- using a concurrent choice operant task. RESULTS NIC pretreatment robustly increased operant responding for the CS+ but did not alter responding for the CS- in the operant choice task (Experiment 3). However, NIC pretreatment did not alter intake or palatability of the CS+ or CS- (Experiments 1 and 2). CONCLUSIONS NIC increases the reinforcing effects of gustatory incentive stimuli, even though these stimuli were not paired with NIC administration. The findings suggest that adding taste incentives to tobacco products may increase the attractiveness of these products to consumers and the probability of repeated use.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, East Tennessee State University, Johnson City, TN 37614, USA.
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13
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Brennan KA, Putt F, Truman P. Nicotine-, tobacco particulate matter- and methamphetamine-produced locomotor sensitisation in rats. Psychopharmacology (Berl) 2013; 228:659-72. [PMID: 23519574 DOI: 10.1007/s00213-013-3071-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 03/08/2013] [Indexed: 12/18/2022]
Abstract
RATIONALE Repeated nicotine exposure produces a weak and transient sensitised locomotor response in rats. Since tobacco smoke contains thousands of non-nicotine chemical constituents, these could alter the sensitised response. OBJECTIVES This study aims to compare the magnitude, persistence and spatial distribution of locomotor sensitisation produced by repeated doses of nicotine, aqueous tobacco particulate matter (TPM) and a positive methamphetamine control. METHODS Male Sprague-Dawley rats received five nicotine (0.0, 0.2 or 0.4 mg/kg), TPM (containing 0.2 or 0.4 mg/kg nicotine) or methamphetamine (0.5 mg/kg) injections every second day, followed by a 4-day withdrawal before the first challenge (Challenge 1, C1). The animals were re-challenged again at 15 days post C1 to test for the persistence of sensitisation (Challenge 2, C2). RESULTS There were no major differences in sensitisation profile between nicotine and TPM. At the lowest 0.2 mg/kg nicotine/TPM dose, however, small differences emerged on select test days. CONCLUSIONS The results indicated that the non-nicotinic agents in TPM did not greatly impact the nicotine-produced locomotor-sensitised response. These findings might suggest that the differential pharmacological properties of TPM do not have major clinical significance. Alternatively, the locomotor model might not expose effects of non-nicotinic constituents, and furthermore, might not closely relate to human tobacco dependence. Different reward-related behavioural models should also be utilised to assess potential effects of non-nicotinic constituents before a role in dependence is discounted.
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Affiliation(s)
- Katharine A Brennan
- School of Psychology, Victoria University of Wellington, P.O. Box 600, Wellington, 6140, New Zealand.
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Nickell JR, Grinevich VP, Siripurapu KB, Smith AM, Dwoskin LP. Potential therapeutic uses of mecamylamine and its stereoisomers. Pharmacol Biochem Behav 2013; 108:28-43. [PMID: 23603417 PMCID: PMC3690754 DOI: 10.1016/j.pbb.2013.04.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 04/01/2013] [Accepted: 04/03/2013] [Indexed: 12/17/2022]
Abstract
Mecamylamine (3-methylaminoisocamphane hydrochloride) is a nicotinic parasympathetic ganglionic blocker, originally utilized as a therapeutic agent to treat hypertension. Mecamylamine administration produces several deleterious side effects at therapeutically relevant doses. As such, mecamylamine's use as an antihypertensive agent was phased out, except in severe hypertension. Mecamylamine easily traverses the blood-brain barrier to reach the central nervous system (CNS), where it acts as a nicotinic acetylcholine receptor (nAChR) antagonist, inhibiting all known nAChR subtypes. Since nAChRs play a major role in numerous physiological and pathological processes, it is not surprising that mecamylamine has been evaluated for its potential therapeutic effects in a wide variety of CNS disorders, including addiction. Importantly, mecamylamine produces its therapeutic effects on the CNS at doses 3-fold lower than those used to treat hypertension, which diminishes the probability of peripheral side effects. This review focuses on the pharmacological properties of mecamylamine, the differential effects of its stereoisomers, S(+)- and R(-)-mecamylamine, and the potential for effectiveness in treating CNS disorders, including nicotine and alcohol addiction, mood disorders, cognitive impairment and attention deficit hyperactivity disorder.
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Affiliation(s)
- Justin R Nickell
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA.
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15
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Panlilio LV, Zanettini C, Barnes C, Solinas M, Goldberg SR. Prior exposure to THC increases the addictive effects of nicotine in rats. Neuropsychopharmacology 2013; 38:1198-208. [PMID: 23314220 PMCID: PMC3656362 DOI: 10.1038/npp.2013.16] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Although it is more common for drug abuse to progress from tobacco to cannabis, in many cases cannabis use develops before tobacco use. Epidemiological evidence indicates that prior cannabis use increases the likelihood of becoming dependent on tobacco. To determine whether this effect might be due to cannabis exposure per se, in addition to any genetic, social, or environmental factors that might contribute, we extended our series of studies on 'gateway drug' effects in animal models of drug abuse. Rats were exposed to THC, the main psychoactive constituent of cannabis, for 3 days (two intraperitoneal injections/day). Then, starting 1 week later, they were allowed to self-administer nicotine intravenously. THC exposure increased the likelihood of acquiring the nicotine self-administration response from 65% in vehicle-exposed rats to 94% in THC-exposed rats. When the price of nicotine was manipulated by increasing the response requirement, THC-exposed rats maintained higher levels of intake than vehicle-exposed rats, indicating that THC exposure increased the value of nicotine reward. These results contrast sharply with our earlier findings that prior THC exposure did not increase the likelihood of rats acquiring either heroin or cocaine self-administration, nor did it increase the reward value of these drugs. The findings obtained here suggest that a history of cannabis exposure might have lasting effects that increase the risk of becoming addicted to nicotine.
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Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Claudio Zanettini
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA,Department of Pharmacology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Chanel Barnes
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Marcelo Solinas
- Experimental and Clinical Neurosciences Laboratory, INSERM U-1084, Poitiers, France,University of Poitiers, Poitiers, France
| | - Steven R Goldberg
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA,Preclinical Pharmacology Section, Biomedical Research Center, National Institute on Drug Abuse, 251 Bayview Boulevard, Baltimore, MD 21224, USA, Tel: +1 443 740 2519, Fax: +1 443 740 2733, E-mail:
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Picciotto MR, Mineur YS. Molecules and circuits involved in nicotine addiction: The many faces of smoking. Neuropharmacology 2013; 76 Pt B:545-53. [PMID: 23632083 DOI: 10.1016/j.neuropharm.2013.04.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 01/26/2023]
Abstract
Tobacco smoking in humans is one of the most persistent and widespread addictions and is driven by nicotine in tobacco smoke. Over the last several decades, understanding of the molecular and cellular basis for nicotine addiction has increased tremendously as a result of pharmacological, molecular genetic, electrophysiological and behavioral studies of nicotine reinforcement. Studies of the biological basis for nicotine reinforcement has helped in the design of new treatments for smoking cessation such as varenicline; however, smokers report that they smoke for many reasons, including the ability to control symptoms of anxiety and depression or the desire to control appetite. Further, developmental exposure to tobacco smoke increases the likelihood of adult smoking. Here we review what is known about the molecular and circuit basis for a number of behaviors related to tobacco smoking. Leveraging the knowledge from studies of different behaviors mediated by nicotine receptors in multiple brain circuits could provide points of convergence that will inform future therapeutic development for smoking cessation. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- Marina R Picciotto
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3rd Floor Research, New Haven, CT 06508, USA.
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17
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Palmatier MI, Marks KR, Jones SA, Freeman KS, Wissman KM, Sheppard AB. The effect of nicotine on sign-tracking and goal-tracking in a Pavlovian conditioned approach paradigm in rats. Psychopharmacology (Berl) 2013; 226:247-59. [PMID: 23090624 DOI: 10.1007/s00213-012-2892-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 10/05/2012] [Indexed: 12/26/2022]
Abstract
RATIONALE Nicotine (NIC) potently increases operant responding for non-NIC reinforcers, and this effect may depend on drug-mediated increases in incentive motivation. According to this hypothesis, NIC should also potently increase approach to Pavlovian-conditioned stimuli associated with rewards. OBJECTIVE The present studies explored the effects of NIC on Pavlovian-conditioned approach responses. METHOD To do so, liquid dippers were used to deliver an unconditioned stimulus (US; 0.1 ml sucrose) after presentation of a conditioned stimulus (CS; 30 s illumination of a stimulus light)-both the CS and US were presented in receptacles equipped to monitor head entries. RESULTS In experiment 1, the CS and US were presented in the same receptacle, but NIC pretreatment (0.4 mg/kg base) did not increase conditioned approach responses. Delivery of the sucrose US was then shifted to receptacle in a different location. All rats learned to approach the new US location (goal-tracking) at similar rates. Approach to the CS receptacle (sign-tracking) declined for saline-pretreated rats, but NIC pretreatment increased sign-tracking. In experiment 2, NIC pretreatment increased sign-tracking when the CS and US were spatially separated during acquisition. In experiment 3, NIC pretreatments were replaced with saline, but the effect of NIC persisted for an additional 24 test sessions. CONCLUSION The findings suggest that NIC increases incentive motivation and that this effect is long-lasting, persisting beyond the pharmacological effects of NIC.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, East Tennessee State University, Johnson City, PO Box 70649, TN 37641, USA.
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18
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Rose EJ, Ross TJ, Salmeron BJ, Lee M, Shakleya DM, Huestis MA, Stein EA. Acute nicotine differentially impacts anticipatory valence- and magnitude-related striatal activity. Biol Psychiatry 2013; 73:280-8. [PMID: 22939991 PMCID: PMC9361221 DOI: 10.1016/j.biopsych.2012.06.034] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 06/06/2012] [Accepted: 06/06/2012] [Indexed: 11/16/2022]
Abstract
BACKGROUND Dopaminergic activity plays a role in mediating the rewarding aspects of abused drugs, including nicotine. Nicotine modulates the reinforcing properties of other motivational stimuli, yet the mechanisms of this interaction are poorly understood. This study aimed to ascertain the impact of nicotine exposure on neuronal activity associated with reinforcing outcomes in dependent smokers. METHODS Smokers (n = 28) and control subjects (n = 28) underwent functional imaging during performance of a monetary incentive delay task. Using a randomized, counterbalanced design, smokers completed scanning after placement of a nicotine or placebo patch; nonsmokers were scanned twice without nicotine manipulation. In regions along dopaminergic pathway trajectories, we considered event-related activity for valence (reward/gain vs. punishment/loss), magnitude (small, medium, large), and outcome (successful vs. unsuccessful). RESULTS Both nicotine and placebo patch conditions were associated with reduced activity in regions supporting anticipatory valence, including ventral striatum. In contrast, relative to controls, acute nicotine increased activity in dorsal striatum for anticipated magnitude. Across conditions, anticipatory valence-related activity in the striatum was negatively associated with plasma nicotine concentration, whereas the number of cigarettes daily correlated negatively with loss anticipation activity in the medial prefrontal cortex only during abstinence. CONCLUSIONS These data suggest a partial dissociation in the state- and trait-specific effects of smoking and nicotine exposure on magnitude- and valence-dependent anticipatory activity within discrete reward processing brain regions. Such variability may help explain, in part, nicotine's impact on the reinforcing properties of nondrug stimuli and speak to the continued motivation to smoke and cessation difficulty.
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Affiliation(s)
- Emma Jane Rose
- Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21228, USA.
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19
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Guy EG, Fletcher PJ. Nicotine-induced enhancement of responding for conditioned reinforcement in rats: role of prior nicotine exposure and α4β2 nicotinic receptors. Psychopharmacology (Berl) 2013; 225:429-40. [PMID: 22885874 DOI: 10.1007/s00213-012-2832-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 07/26/2012] [Indexed: 11/24/2022]
Abstract
RATIONALE Stimuli associated with nicotine can become motivationally significant and may play a role in tobacco dependence. Previous work indicates that nicotine enhances responding for a conditioned reinforcer (CR). OBJECTIVES These studies examined the effects of prior exposure to nicotine on responding for a CR, persistence of this response, and the role of α4β2 or α7 nicotinic receptor subtypes. METHODS Water deprived rats were given 13 Pavlovian conditioning sessions where a light/tone conditioned stimulus (CS) was paired with the delivery of water. Then, rats were presented with two levers: one delivered the CS (now a CR), the other was inactive. Experiments examined the effect of nicotine administered prior to Pavlovian conditioning sessions on approach behavior during CS presentations, operant responding for CR in the presence and absence of nicotine, and the persistence of responding for CR. The effects of nicotinic acetylcholine receptor (nAChR) antagonism with mecamylamine and α4β2 or α7 nAChR antagonism with dihydro-beta-erythroidine (DHβE) or methyllycaconitine (MLA) on nicotine-enhanced responding for CR were examined. RESULTS Nicotine enhanced approach behavior during CS presentations and potentiated operant responding for CR, an effect sensitized as a result of nicotine exposure during conditioning. Responding for CR and its potentiation by nicotine was stable over multiple tests. Enhanced responding for the CR induced by nicotine was blocked by mecamylamine and DHβE, but not MLA. CONCLUSIONS Nicotine enhances Pavlovian discriminated approach and shows sensitized nicotine-induced enhancements in responding for CR, an effect depending on α4β2 nAChRs.
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Palmatier MI, O'Brien LC, Hall MJ. The role of conditioning history and reinforcer strength in the reinforcement enhancing effects of nicotine in rats. Psychopharmacology (Berl) 2012; 219:1119-31. [PMID: 21861095 DOI: 10.1007/s00213-011-2439-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 08/05/2011] [Indexed: 12/26/2022]
Abstract
RATIONALE Nicotine (NIC) administration can increase behaviors that result in delivery of non-drug reinforcers (e.g., salient sensory stimuli). However, little is known about the circumstances under which NIC increases these behaviors. OBJECTIVE The present studies sought to extend the reinforcement enhancing effects of NIC to sucrose rewards for which intensity could be systematically manipulated. METHOD In Experiment 1, rats were trained to respond for sucrose (30% w/v) on a progressive ratio (PR) schedule of reinforcement and were pretreated with NIC (0.4 mg/kg free-base) or physiological saline (SAL). The intensity of the sucrose reward was manipulated over subsequent testing sessions (0-60% w/v). Similar procedures were used in Experiment 2; however, each subject received only one sucrose concentration (0-20%) to control for conditioning history. In Experiment 3, a fixed ratio 3 (FR3) schedule of reinforcement was used to investigate putative activating effects of NIC. Experiment 4 investigated whether NIC pretreatment would reduce sucrose intake in limited-access drinks. RESULTS In Experiment 1, NIC increased the motivation to obtain all sucrose concentrations, including water. However, when conditioning history was controlled (Experiment 2) the reinforcement enhancing effects of NIC were systematically related to the strength of the reinforcer. In Experiment 3, NIC neither increased nor decreased responding for sucrose. In Experiment 4, NIC reduced sucrose intake, but only at concentrations that resulted in peak drink volumes (5-20%). CONCLUSION The results suggest that the reinforcement enhancing effects of NIC depend on conditioning history and do not appear to be the result of simple behavioral activation.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, Kansas State University, 469 Bluemont Hall, 1100 Mid Campus Drive, Manhattan, KS 66506, USA.
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21
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Donny EC, Caggiula AR, Sweitzer M, Chaudhri N, Gharib M, Sved AF. Self-administered and yoked nicotine produce robust increases in blood pressure and changes in heart rate with modest effects of behavioral contingency in rats. Pharmacol Biochem Behav 2011; 99:459-67. [PMID: 21554897 DOI: 10.1016/j.pbb.2011.04.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/29/2011] [Accepted: 04/21/2011] [Indexed: 11/28/2022]
Abstract
Experimenter-administered nicotine produces reliable increases in blood pressure and changes in heart rate. However, an extensive literature demonstrates that the effects of psychoactive drugs are dependent on whether administration is contingent on behavior. The present study assessed the cardiovascular effects of nicotine and whether those effects vary as a function of whether nicotine was self-administered or response-independent. Rats were divided into three groups according to a yoked design. The pattern of infusions for each triad was determined by the animal self-administering nicotine; the other two animals received either yoked nicotine or saline. Heart rate and blood pressure were measured during eighteen daily, 1h drug sessions by radiotelemetry. Each session was preceded and followed by a 20 minute period during which cardiovascular function was monitored in the operant chambers, but drug was not available. Acute exposure to yoked nicotine produced a rapid rise in blood pressure that was larger than the increase observed with self-administered nicotine. Additional infusions during the first session resulted in a similar sustained elevation in blood pressure in the nicotine groups. Over subsequent sessions, self-administered nicotine produced a larger effect on systolic blood pressure particularly early in each session, although for both self-administered and yoked nicotine the hypertensive effects waned partially with repeated test sessions. This decrease was fully accounted for by a pre-session decrease in pressure; relative to pre-session levels the strong hypertensive effects of nicotine persisted. Initial exposure to nicotine produced a short-lived bradycardia that in subsequent sessions was replaced with a longer-lasting nicotine-induced tachycardia; neither effect was related to the behavioral contingency of nicotine delivery. Together, these data provide a rich picture of the cardiovascular effects of nicotine. Effects of behavioral contingency were observed, but differences were limited. Other non-pharmacological factors such as baseline shifts potentially related to nicotine-associated cues deserve further attention.
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Affiliation(s)
- Eric C Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA.
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22
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Paterson NE. Translational research in addiction: toward a framework for the development of novel therapeutics. Biochem Pharmacol 2011; 81:1388-407. [PMID: 21216239 DOI: 10.1016/j.bcp.2010.12.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/13/2010] [Accepted: 12/15/2010] [Indexed: 12/16/2022]
Abstract
The development of novel substance use disorder (SUD) therapeutics is insufficient to meet the medical needs of a growing SUD patient population. The identification of translatable SUD models and tests is a crucial step in establishing a framework for SUD therapeutic development programs. The present review begins by identifying the clinical features of SUDs and highlights the narrow regulatory end-point required for approval of a novel SUD therapeutic. A conceptual overview of dependence is provided, followed by identification of potential intervention targets in the addiction cycle. The main components of the addiction cycle provide the framework for a discussion of preclinical models and their clinical analogs, all of which are focused on isolated behavioral end-points thought to be relevant to the persistence of compulsive drug use. Thus, the greatest obstacle to successful development is the gap between the multiplicity of preclinical and early clinical end-points and the regulatory end-point of sustained abstinence. This review proposes two pathways to bridging this gap: further development and validation of the preclinical extended access self-administration model; inclusion of secondary end-points comprising all of the measures highlighted in the present discussion in Phase 3 trials. Further, completion of the postdictive validation of analogous preclinical and clinical assays is of high priority. Ultimately, demonstration of the relevance and validity of a variety of end-points to the ultimate goal of abstinence will allow researchers to identify truly relevant therapeutic mechanisms and intervention targets, and establish a framework for SUD therapeutic development that allows optimal decision-making and resource allocation.
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Affiliation(s)
- Neil E Paterson
- Behavioral Pharmacology, PsychoGenics, Inc., 765 Old Saw Mill River Rd., Tarrytown, NY 10591, USA.
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23
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Wing VC, Shoaib M. A second-order schedule of food reinforcement in rats to examine the role of CB1 receptors in the reinforcement-enhancing effects of nicotine. Addict Biol 2010; 15:380-92. [PMID: 20331564 DOI: 10.1111/j.1369-1600.2009.00203.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Nicotine is believed to enhance the motivational value of reinforcers. Although endogenous cannabinoids acting on CB1 receptors have been implicated in the motivational effects of nicotine, their role in the 'reinforcement-enhancing' properties of nicotine is unknown. This study compared the effect of acute and chronic non-contingent nicotine administration on responding for an unconditioned reinforcing stimulus (UCS) and a visual conditioned stimulus (CS) and the role of CB1 receptors was examined. Male hooded Lister rats were trained on a second-order schedule [FI 15' (FR5: S)] under which presentation of the CS (5s/5Hz light oscillation) was intermittently reinforced by the UCS (food). The rats were treated with daily saline or nicotine (0.4 mg/kg, subcutaneous [s.c.]) throughout the study. The effect of the acute nicotine challenge (0.05, 0.1 and 0.2 mg/kg, s.c.) and the CB1 receptor antagonist AM251 (0.1, 0.3 and 1 mg/kg, intraperitoneal [i.p.]) on responding for the CS and/or UCS was examined. The acute nicotine challenge increased responding for both the UCS and CS in the rats chronically treated with nicotine, an effect which was less robust in the nicotine-naive rats. AM251 significantly reduced responding for the UCS and CS, and an interaction with the nicotine challenge was found. These data support and extend the hypothesis that nicotine can enhance the motivational value of reinforcing stimuli and suggest the increases in responding produced by nicotine involve CB1 receptors. Furthermore, this study highlights the utility of second-order schedules of reinforcement for investigation of the neural circuits underlying the reinforcement-enhancing effects of nicotine.
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MESH Headings
- Animals
- Appetitive Behavior/drug effects
- Appetitive Behavior/physiology
- Association Learning/drug effects
- Association Learning/physiology
- Brain/drug effects
- Brain/physiopathology
- Conditioning, Classical/drug effects
- Dose-Response Relationship, Drug
- Injections, Intraperitoneal
- Male
- Motivation/drug effects
- Motivation/physiology
- Nicotine/pharmacology
- Piperidines/pharmacology
- Pyrazoles/pharmacology
- Rats
- Rats, Inbred Strains
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/drug effects
- Receptor, Cannabinoid, CB1/physiology
- Reinforcement Schedule
- Tobacco Use Disorder/physiopathology
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Affiliation(s)
- Victoria C Wing
- Psychobiology Research Laboratories, Institute of Neuroscience, Newcastle University, UK
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Nicotine and cocaine self-administration using a multiple schedule of intravenous drug and sucrose reinforcement in rats. Behav Pharmacol 2010; 21:182-93. [PMID: 20440201 DOI: 10.1097/fbp.0b013e32833a5c9e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There appears to be a relatively narrow range of contingencies in which intravenous (i.v) infusions of nicotine will maintain responding in rats. The schedule of reinforcement typically used when investigating i.v. nicotine self-administration is a simple fixed-ratio (FR) schedule. This study determined if responding in rats could be established using a multiple schedule of either i.v. cocaine or nicotine and sucrose reinforcement. Following training of individual components with each reinforcer, rats were placed on an FR15 60-s timeout multiple schedule of cocaine (0.3 mg/kg/infusion) and sucrose (45 mg pellets) reinforcement or an FR5 60-s timeout multiple schedule of nicotine (0.03 mg/kg/infusion) and sucrose (45 mg pellets) reinforcement. Both cocaine and nicotine maintained significant levels of responding under the multiple schedule. Pretreatment with the dopamine D1 antagonist SCH 23390 increased cocaine-maintained responding, but not sucrose responding. Acute pretreatment with the nicotinic antagonist mecamylamine or SCH 23390 specifically decreased nicotine self-administration. Extinction of the individual nicotine and sucrose components resulted in decreases in responding in each component under extinction. These results indicate that i.v. nicotine maintains responding under a multiple schedule. This procedure may be useful when studying the specificity of drug pretreatments on nicotine self-administration.
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Palmatier MI, Levin ME, Mays KL, Donny EC, Caggiula AR, Sved AF. Bupropion and nicotine enhance responding for nondrug reinforcers via dissociable pharmacological mechanisms in rats. Psychopharmacology (Berl) 2009; 207:381-90. [PMID: 19760281 PMCID: PMC2884399 DOI: 10.1007/s00213-009-1666-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 09/01/2009] [Indexed: 01/11/2023]
Abstract
RATIONALE Nicotine serves as a primary reinforcer but also potently enhances responding for nonnicotine stimuli with reinforcing properties. One of the most successful pharmacotherapies for smoking cessation, bupropion, also increases responding for nondrug reinforcers such as food and brain stimulation rewards. OBJECTIVE The present studies investigated whether treatment with bupropion and nicotine had similar effects on responding for a reinforcing visual stimulus (VS). They also investigated whether the effects of bupropion and nicotine depended on common pharmacological substrates. RESULTS Nicotine (0.4 mg/kg base) enhanced responding for the VS, and this enhancing effect increased across testing sessions, replicating our previous findings. Bupropion (3, 10, and 30 mg/kg salt) dose-dependently increased responding for the VS. Treatment with 10 and 30 mg/kg bupropion resulted in a profile similar to nicotine; operant responding increased over repeated drug treatments. The reinforcement enhancing effect of nicotine, but not bupropion, was blocked by pretreatment with the nicotinic acetylcholine receptor antagonist mecamylamine. In contrast, the reinforcement enhancing effect of bupropion, but not nicotine, was blocked by pretreatment with the alpha noradrenergic antagonist prazosin. CONCLUSION The reinforcement enhancing effects of nicotine and bupropion increased over time and repeated treatments suggesting a shared mechanism of action. However, the reinforcement enhancing effects of nicotine are mediated by nicotinic acetylcholine receptors, whereas the reinforcement enhancing effects of bupropion were mediated by alpha noradrenergic receptors.
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Affiliation(s)
- Matthew I. Palmatier
- Department of Psychology, Kansas State University, Manhattan, KS 66502,Address Correspondence To: Matthew I. Palmatier, Department of Psychology, Kansas State University, 469 Bluemont Hall, Manhattan, KS 66502
| | - Melissa E. Levin
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260
| | - Kara L. Mays
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
| | - Eric C. Donny
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260
| | | | - Alan F. Sved
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
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Clemens KJ, Caillé S, Stinus L, Cador M. The addition of five minor tobacco alkaloids increases nicotine-induced hyperactivity, sensitization and intravenous self-administration in rats. Int J Neuropsychopharmacol 2009; 12:1355-66. [PMID: 19366487 DOI: 10.1017/s1461145709000273] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several minor tobacco alkaloids have been found to exhibit properties pharmacologically relevant to the addictive profile of tobacco; however, little is known of their effects on a behavioural model of drug addiction. In this study we compared the locomotor and reinforcing effects of intravenous nicotine (30 microg/kg per infusion) vs. a cocktail of nicotine plus five minor alkaloids found in tobacco smoke (anabasine, nornicotine, anatabine, cotinine and myosmine). Rats were initially tested for their locomotor response to nicotine or nicotine plus the minor alkaloids with six intravenous injections over 1 h. We then assessed the spontaneous acquisition of intravenous self-administration with nicotine or nicotine plus the minor alkaloids, under a fixed-ratio 1 schedule followed by responding on a fixed-ratio 5 schedule, progressive-ratio schedule and a single within-session ascending dose-response test. The activity test was repeated following the progressive-ratio phase to assess locomotor sensitization. A second group of rats were then tested on the locomotor procedure to better clarify the role of each individual minor alkaloid in nicotine-induced locomotor activity. Compared to nicotine alone, addition of the minor tobacco alkaloids increased locomotor activity and increased locomotor sensitization following self-administration. During fixed-ratio 5, progressive ratio and the dose-response test, rats receiving nicotine plus the minor alkaloids responded significantly more than those receiving nicotine alone. Testing of each minor alkaloid in the second experiment indicated that anatabine, cotinine and myosmine individually increased nicotine-induced locomotor activity. These results suggest that the minor tobacco alkaloids, particularly anatabine, cotinine and myosmine, may increase the motivation for nicotine and thus facilitate smoking behaviour.
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Affiliation(s)
- Kelly J Clemens
- CNRS UMR 5227, Team Neuropsychopharmacology of Addiction, University of Bordeaux 1 and 2, Bordeaux, France.
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27
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Dwoskin LP, Smith AM, Wooters TE, Zhang Z, Crooks PA, Bardo MT. Nicotinic receptor-based therapeutics and candidates for smoking cessation. Biochem Pharmacol 2009; 78:732-43. [PMID: 19523455 PMCID: PMC4110684 DOI: 10.1016/j.bcp.2009.06.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 05/29/2009] [Accepted: 06/01/2009] [Indexed: 12/29/2022]
Abstract
Tobacco dependence is the most preventable cause of death and is a chronic, relapsing disorder in which compulsive tobacco use persists despite known negative health consequences. All currently available cessation agents (nicotine, varenicline and bupropion) have limited efficacy and are associated with high relapse rates, revealing a need for more efficacious, alternative pharmacotherapies. The major alkaloid in tobacco, nicotine, activates nicotinic receptors (nAChRs) which increase brain extracellular dopamine producing nicotine reward leading to addiction. nAChRs are located primarily presynaptically and modulate synaptic activity by regulating neurotransmitter release. Subtype-selective nAChR antagonists that block reward-relevant mesocorticolimbic and nigrostriatal dopamine release induced by nicotine may offer advantages over current therapies. An innovative approach is to provide pharmacotherapies which are antagonists at nAChR subtypes mediating nicotine evoked dopamine release. In addition, providing multiple medications with a wider array of targets and mechanisms should provide more treatment options for individuals who are not responsive to the currently available pharmacotherapies. This review summarizes the currently available smoking cessation therapies and discusses emerging potential therapeutic approaches employing pharmacological agents which act as antagonists at nicotinic receptors.
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Affiliation(s)
- Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA.
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Perkins KA. Acute responses to nicotine and smoking: implications for prevention and treatment of smoking in lower SES women. Drug Alcohol Depend 2009; 104 Suppl 1:S79-86. [PMID: 19084357 DOI: 10.1016/j.drugalcdep.2008.10.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 10/22/2008] [Accepted: 10/30/2008] [Indexed: 10/21/2022]
Abstract
Compared with men, smoking reward and reinforcement in women tend to be less sensitive to nicotine but more sensitive to the nonpharmacological aspects of cigarette smoking (e.g. cues). Drawing mostly on findings from our laboratory, including new analyses of existing data, we explored whether characteristics possibly related to socioeconomic status (SES) may moderate acute responses to nicotine or smoking in women. Effects of nicotine in nonsmokers and in smokers were thought to identify factors that may be involved in the onset of nicotine dependence and in persistence of dependence, respectively. In nonsmokers, impulsive personality, prior marijuana use, and DRD2 and DRD4 genotypes may moderate nicotine responses in men but apparently not in women. However, the DRD4 gene may alter smoking reinforcement in response to negative mood in women but not men, a finding that could help explain smoking persistence in low SES women. Increasing women smoker's quit motivation via monetary reinforcement for abstinence may enhance the efficacy of nicotine patch during a quit attempt, at least in the short run. These findings clearly are tentative and require replication and extension in larger samples. A potentially more promising area of research concerns the recent finding from animal research that nicotine may enhance the reinforcing value of other reinforcers unrelated to smoking. Such an effect could increase our understanding of why quitting smoking is so difficult, why lapses after a quit attempt strongly predict failure of that attempt, and why nicotine replacement therapy aids cessation. Although speculative, low SES smokers may find smoking particularly hard to give up if doing so results in an overall decline in reinforcement, but they may gain more relative benefit from nicotine replacement therapy during quit attempts.
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Affiliation(s)
- Kenneth A Perkins
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
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Lack of reinforcement enhancing effects of nicotine in non-dependent smokers. Psychopharmacology (Berl) 2009; 205:635-45. [PMID: 19488740 DOI: 10.1007/s00213-009-1574-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE Recent animal research has shown that, aside from its primary and secondary reinforcing effects, nicotine may enhance reinforcement from stimuli unrelated to nicotine intake. Little human research has directly examined this potentially important influence of nicotine. OBJECTIVES We report two virtually identical studies examining the influence of nicotine, via nasal spray (study 1) and cigarettes (study 2), on the reinforcing effects of rewards unrelated to nicotine intake. MATERIALS AND METHODS Both studies involved young adults with some past smoking exposure but no history of nicotine dependence. Reinforcement was assessed by responses on a simple operant computer task reinforced by: money, music, the termination of aversive noise, or no reward (control). Participants responded for rewards on three separate sessions, involving intermittent dosing of 0, 5, or 10 microg/kg nicotine via nasal spray (study 1) or the smoking of 0.05 or 0.6 mg nicotine cigarettes or no smoking (study 2). RESULTS Results showed no effects of nicotine, by nasal spray or cigarette smoking, on reinforced responses, although nicotine increased some subjective responses (e.g. head rush/buzzed, liking). Nicotine via smoking also did not influence affect or hedonic ratings of slides varying in mood valence in an exploratory trial in study 2. CONCLUSIONS These results do not support the notion that nicotine per se enhances the reinforcing value of other reinforcers in humans. Any reinforcement enhancing effects of nicotine in humans may be specific to dependent smokers or may be relatively narrow and dependent upon procedural conditions different from those in the current studies.
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The neuropharmacological substrates of nicotine reward: reinforcing versus reinforcement-enhancing effects of nicotine. Behav Pharmacol 2009; 20:211-25. [PMID: 19421028 DOI: 10.1097/fbp.0b013e32832c7083] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Compulsive nicotine use is thought to be maintained by the acute reinforcing effects of nicotine and the reinforcement-enhancing effects of nicotine, in addition to the negative consequences of nicotine abstinence. Nicotine self-administration and nicotine-induced enhancement of non-nicotine reinforcers such as intracranial self-stimulation provide measures of these dual rewarding properties of nicotine. First, pharmacological manipulations that modulate the reinforcing and reinforcement-enhancing effects of nicotine are identified and discussed. Second, the interpretation and implications of data that identified shared and specific pharmacological substrates underlying the dual rewarding effects of nicotine are discussed, including implications for the preclinical testing of putative antismoking medications. In conclusion, reinforcement-related behaviors that are mediated by central reinforcement processes are likely to, and generally do, exhibit a number of common pharmacological substrates. Interestingly, however, a few pharmacological classes of compounds seem to exert selective effects on components of the dual nicotine reward mechanisms, indicating differences in the pharmacological substrates of the reinforcing and reinforcement-enhancing effects of nicotine. Further characterization of such compounds may ultimately lead to the identification of novel medications for nicotine dependence in humans.
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Le Foll B, Goldberg SR. Effects of nicotine in experimental animals and humans: an update on addictive properties. Handb Exp Pharmacol 2009:335-67. [PMID: 19184655 PMCID: PMC2687081 DOI: 10.1007/978-3-540-69248-5_12] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Tobacco use through cigarette smoking is the leading preventable cause of death in the developed world. Nicotine, a psychoactive component of tobacco, appears to play a major role in tobacco dependence, but the reinforcing effects of nicotine have often been difficult to demonstrate directly in controlled studies with laboratory animals or human subjects. Here we update our earlier review published in Psychopharmacology (Berl) in 2006 on findings obtained with various procedures developed to study dependence-related behavioral effects of nicotine in experimental animals and humans. Results obtained with drug self-administration, conditioned place preference, subjective reports of nicotine effects and nicotine discrimination indicate that nicotine can function as an effective reinforcer of drug-seeking and drug-taking behavior both in experimental animals and humans under appropriate conditions. Interruption of chronic nicotine exposure produces ratings of drug withdrawal and withdrawal symptoms that may contribute to relapse. Difficulties encountered in demonstrating reinforcing effects of nicotine under some conditions, relative to other drugs of abuse, may be due to weaker primary reinforcing effects of nicotine, to aversive effects produced by nicotine, or to a more critical contribution of environmental stimuli to the maintenance of drug-seeking and drug-taking behavior with nicotine than with other drugs of abuse. Several recent reports suggest that other chemical substances inhaled along with nicotine in tobacco smoke may play a role in sustaining smoking behavior. However, conflicting results have been obtained with mice and rats and these findings have not yet been validated in nonhuman primates or human subjects. Taken together, these findings suggest that nicotine acts as a typical drug of abuse in experimental animals and humans in appropriate situations.
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Affiliation(s)
- Bernard Le Foll
- Translational Addiction Research Laboratory, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
| | - Steven R. Goldberg
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, Maryland, USA
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Palmatier MI, Coddington SB, Liu X, Donny EC, Caggiula AR, Sved AF. The motivation to obtain nicotine-conditioned reinforcers depends on nicotine dose. Neuropharmacology 2008; 55:1425-30. [PMID: 18809417 PMCID: PMC2873860 DOI: 10.1016/j.neuropharm.2008.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 09/01/2008] [Accepted: 09/02/2008] [Indexed: 11/15/2022]
Abstract
Stimuli associated with nicotine (NIC) can acquire new meaning via Pavlovian conditioning. If a stimulus is associated with the primary reinforcing effects of NIC, the new conditional properties of the stimulus should make it a more valuable reinforcer (i.e., increase the motivation to obtain the stimulus), and this value should be based, in part, on the strength or intensity of the primary reinforcer (i.e., NIC dose). The purpose of the present study was to investigate whether NIC-conditioned reinforcement increased motivation to obtain non-NIC stimuli, as reflected by performance on a progressive ratio (PR) reinforcement schedule, and whether this increased motivation was systematically related to NIC dose. Two Paired groups were allowed to nose-poke for NIC (0.03 or 0.09mg/kg/infusion, IV) accompanied by 15-s illumination of a stimulus light (conditional stimulus or CS). Two Unpaired groups (0.03 or 0.09mg/kg/infusion) could also make a nose-poke response for the CS; however their NIC infusions were controlled by the Paired group (i.e., yoked design). A fifth group (CS-Only) was allowed to nose-poke for CS presentations and saline infusions. After 29 conditioning sessions the nose-poke operant was prevented by obscuring the receptacle and the CS (accompanied by saline infusion for all groups) was made contingent upon a novel operant response (lever press). During the acquisition of this novel response, each CS/saline infusion earned increased the number of responses required to earn the next CS/saline infusion. Pairings with the primary reinforcing effects of NIC resulted the acquisition of a novel response for the CS. Motivation to obtain the CS depended on salience (dose) of the primary reinforcement (NIC).
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Affiliation(s)
- M I Palmatier
- Department of Psychology, Kansas State University, 469 Bluemont Hall, 1100 Mid Campus Drive, Manhattan, KS 66502, USA.
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Metabotropic glutamate 5 receptor (mGluR5) antagonists decrease nicotine seeking, but do not affect the reinforcement enhancing effects of nicotine. Neuropsychopharmacology 2008; 33:2139-47. [PMID: 18046312 PMCID: PMC2812904 DOI: 10.1038/sj.npp.1301623] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nicotine self-administration models typically evaluate the effects of smoking cessation aides on 'primary reinforcement' engendered by nicotine. However, the more recently described reinforcement enhancing effects of the drug are not always included in experimental analyses of potential therapeutics. We evaluated the effects of pretreatment with noncompetitive antagonists of the metabotropic glutamate 5 receptor (mGluR5) on each reinforcement-related effect of nicotine using a model in which a reinforcing visual stimulus (VS) and nicotine infusions were concurrently available. Five groups (2-lever, VS-only, NIC+VS, NIC-only, or SAL-only) were instrumented for self-administration. The 2-lever group could earn a nicotine infusion (0.06 mg/kg per infusion free base) for meeting the schedule on one lever (eg right), or VS for meeting the schedule on the other lever (eg left). The VS-only group could earn VS or saline under similar contingencies. Remaining rats could press one lever to earn both reinforcers (NIC+VS), nicotine infusions (NIC-only), or saline infusions (SAL-only); the other lever was 'inactive'. Responding on the VS lever in the 2-lever group was greater than that of the VS-only group, reflecting the reinforcement-enhancing effect of nicotine. Pretreatment with 2-methyl-6-(phenylethynyl)-pyridine (MPEP) or 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) decreased nicotine intake as well as the enhanced responding for the concurrently available VS. In follow-up studies, replacing nicotine via experimenter-administered infusions sustained the drugs reinforcement enhancing effect; neither MPEP nor MTEP decreased the enhancing effects of nicotine. These findings are consistent with other studies suggesting that mGlu5 receptors mediate nicotine seeking, but do not alter the reinforcement enhancing effects of nicotine.
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The role of nicotine in smoking: a dual-reinforcement model. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2008; 55:91-109. [PMID: 19013940 DOI: 10.1007/978-0-387-78748-0_6] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Models of intravenous nicotine self-administration in laboratory animals are being used to investigate the behavioral and neurobiological consequences of nicotine reinforcement, and to aid in the development of novel pharmacotherapies for smoking cessation. Central to these models is the principle of primary reinforcement, which posits that response-contingent presentation of a primary reinforcer, nicotine, engenders robust operant behavior, whereas response-independent drug delivery does not. This dictum of nicotine as a primary reinforcer has been widely used to explain why people smoke tobacco-smoking results in the rapid delivery of nicotine to the brain, setting up a cascade of neurobiological processes that strengthen subsequent smoking behavior. However, there is mounting evidence that the primary reinforcement model of nicotine self-administration fails to fully explain existing data from both the animal self-administration and human smoking literatures. We have recently proposed a "dual reinforcement" model to more fully capture the relationship between nicotine and self-administration, including smoking. Briefly, the "dual reinforcement" model posits that nicotine acts as both a primary reinforcer and a reinforcement enhancer. The latter action of nicotine had originally been uncovered by showing that a reinforcing VS, which accompanies nicotine delivery, synergizes with nicotine in the acquisition and maintenance of self-administration, and that this synergism can be reproduced by combining operant responding for the reinforcing stimulus with non-contingent (response-independent) nicotine. Thus, self-administration (and smoking) is sustained by three actions: (1) nicotine, acting as a primary reinforcer, can sustain behavior that leads to its delivery; (2) nicotine, acting as a primary reinforcer, can establish neutral environmental stimuli as conditioned reinforcers through Pavlovian associations; and (3) nicotine, acting as a reinforcement enhancer, can magnify the incentive value of accompanying stimuli, be they conditioned or unconditioned reinforcers.
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Dwoskin LP, Pivavarchyk M, Joyce BM, Neugebauer NM, Zheng G, Zhang Z, Bardo MT, Crooks PA. Targeting reward-relevant nicotinic receptors in the discovery of novel pharmacotherapeutic agents to treat tobacco dependence. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2008; 55:31-63. [PMID: 19013938 DOI: 10.1007/978-0-387-78748-0_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0082, USA.
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Palmatier MI, Liu X, Matteson GL, Donny EC, Caggiula AR, Sved AF. Conditioned reinforcement in rats established with self-administered nicotine and enhanced by noncontingent nicotine. Psychopharmacology (Berl) 2007; 195:235-43. [PMID: 17676401 PMCID: PMC2811394 DOI: 10.1007/s00213-007-0897-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 07/07/2007] [Indexed: 01/19/2023]
Abstract
RATIONALE Nicotine is widely assumed to convey reinforcing properties upon tobacco-related stimuli through associative learning. We have proposed that the reinforcement derived from these conditional stimuli can be inflated by a nonassociative "reinforcement-enhancing" effect of nicotine. OBJECTIVES Experiment 1 investigated whether nicotine could establish a stimulus as a conditioned reinforcer. Using the same subjects, Experiment 2 examined whether responding for a nicotine-associated stimulus was enhanced by response-independent administration of nicotine. MATERIALS AND METHODS Self-administered nicotine (Paired group, 0.03 mg kg(1) infusion(-1)) or saline (conditional stimulus or CS-Only group) was paired with a stimulus light (CS). An Unpaired group, yoked to the Paired group, received equal exposure to nicotine and the CS, but each event was temporally separated. To test for conditioning, the CS was then made contingent upon a novel lever-pressing response. In Experiment 2, a subset of the paired rats (self-administering) continued to lever press while receiving contingent nicotine and the CS. To determine whether nicotine enhanced responding for the CS, two remaining subsets of the Paired group responded for the CS while receiving nicotine (YNIC) or saline (YSAL) yoked to the self-administering rats. All remaining control groups received response-contingent CS presentations, together with yoked nicotine or saline. RESULTS Pairing self-administered nicotine with the CS promoted the acquisition of a novel response for the CS. In Experiment 2, the Paired YNIC group responded at higher rates than control groups receiving YNIC or YSAL. CONCLUSIONS Nicotine can establish stimuli as conditioned reinforcers for which noncontingent nicotine can enhance responding.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, University of Pittsburgh, 3137 Sennott Square, Pittsburgh, PA 15260, USA.
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Affiliation(s)
- Neil E Grunberg
- Department of Medical and Clinical Psychology and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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Lerman C, LeSage MG, Perkins KA, O'Malley SS, Siegel SJ, Benowitz NL, Corrigall WA. Translational research in medication development for nicotine dependence. Nat Rev Drug Discov 2007; 6:746-62. [PMID: 17690709 DOI: 10.1038/nrd2361] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A major obstacle to the development of medications for nicotine dependence is the lack of animal and human laboratory models with sufficient predictive clinical validity to support the translation of knowledge from laboratory studies to clinical research. This Review describes the animal and human laboratory paradigms commonly used to investigate the pathophysiology of nicotine dependence, and proposes how their predictive validity might be determined and improved, thereby enhancing the development of new medications.
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Affiliation(s)
- Caryn Lerman
- Department of Psychiatry and Abramson Cancer Center, University of Pennsylvania, 3535 Market Street, Suite 4100, Philadelphia, Pennsylvania 19104, USA.
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Palmatier MI, Matteson GL, Black JJ, Liu X, Caggiula AR, Craven L, Donny EC, Sved AF. The reinforcement enhancing effects of nicotine depend on the incentive value of non-drug reinforcers and increase with repeated drug injections. Drug Alcohol Depend 2007; 89:52-9. [PMID: 17240084 PMCID: PMC1955684 DOI: 10.1016/j.drugalcdep.2006.11.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 11/21/2006] [Accepted: 11/27/2006] [Indexed: 12/20/2022]
Abstract
We have hypothesized that nicotine has two effects on reinforcement; it increases the probability of responses resulting in nicotine delivery (primary reinforcement) and enhances the apparent reward value of non-nicotine reinforcers (reinforcement enhancing effect). The present studies investigated two predictions generated by this hypothesis: (1) that the reinforcement enhancing effect will depend on apparent stimulus reward value and (2) that the temporal profile of this effect would depend on the pharmacological profile of nicotine. In Experiment 1, rats were trained to lever press for one of two audio-visual stimuli that differed in their intrinsic reinforcing value and then the effect of pre-session nicotine (0.4 mg/kg base) or saline injections was tested. The stimulus that supported very low rates of operant responding displayed smaller increases in responding after pre-session injections of nicotine. In Experiment 2 the effect of nicotine injected 5 min before the session was compared to the effect of nicotine injected 1h after the session using the more reinforcing stimulus condition from the first experiment. A control group received only vehicle injections. In contrast to nicotine injected just prior to the session, post-session injections of nicotine had no detectable effect on responding for the more reinforcing stimulus. These results indicate that the reinforcement enhancing action of nicotine depends on the intensity of the primary reinforcer and that enhanced reinforcement by nicotine depends on coincident access to a stimulus with reinforcing properties.
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Affiliation(s)
- Matthew I Palmatier
- Department of Psychology, University of Pittsburgh, 3137 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA.
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