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Truman P, Atigari DV, Kidwell M, Colussi-Mas J, Ellenbroek B. The effect of mixed tobacco monoamine oxidase inhibitors in animal models relevant to tobacco dependence. Psychopharmacology (Berl) 2024:10.1007/s00213-024-06712-8. [PMID: 39556208 DOI: 10.1007/s00213-024-06712-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2024] [Accepted: 10/30/2024] [Indexed: 11/19/2024]
Abstract
RATIONALE Tobacco monoamine oxidase (MAO) inhibitors have long been suspected of influencing tobacco dependence, but direct evidence of their effects has been difficult to obtain. Recently we have identified two new groups of monoamine oxidase inhibitors, hydroquinones and polyunsaturated fatty acids (linoleic and linolenic acid), abundant in tobacco smoke. OBJECTIVES To test, in relevant animal models, whether the combined effect of these inhibitors is sufficient to affect addictive responses to nicotine. METHODS Here we report the first tests of the effects of mixed tobacco MAO inhibitors in three animal behavioural tests relevant to nicotine addiction, conditioned place preference, locomotor sensitisation and nicotine self-administration. Inhibitors used were the aforementioned linoleic and linolenic acid, and catechol, 4-ethylcatechol, 4-methyl catechol and hydroquinone, together with the already known inhibitors harman and norharman. They were administered together in the ratios found in tobacco smoke. RESULTS In conditioned place preference and in self-administration tests the addition of these tobacco MAO inhibitors significantly increased responding to nicotine and motivation to self-administer nicotine, supporting the hypothesis that inhibition of MAO enzymes in the brain enhances addictive responses such as that for nicotine. The combined MAO inhibitors without nicotine did not cause increased locomotor activity and did not induce a place conditioned response. CONCLUSIONS Our results show that the combined effect of three groups of major MAO inhibitors present in tobacco smoke can enhance the addictive responses to nicotine in rats. There is no evidence from this study that these MAO inhibitors are addictive in themselves.
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Affiliation(s)
- Penelope Truman
- School of Health Sciences, Massey University, Wellington, New Zealand.
| | | | - Meyrick Kidwell
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand
| | - Joyce Colussi-Mas
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Bart Ellenbroek
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand
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2
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Harris AC, Muelken P, Alcheva A, Stepanov I, LeSage MG. Cigarette Smoke Extract, but Not Electronic Cigarette Aerosol Extract, Inhibits Monoamine Oxidase in vitro and Produces Greater Acute Aversive/Anhedonic Effects Than Nicotine Alone on Intracranial Self-Stimulation in Rats. Front Neurosci 2022; 16:868088. [PMID: 35712461 PMCID: PMC9196039 DOI: 10.3389/fnins.2022.868088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/25/2022] [Indexed: 12/14/2022] Open
Abstract
Conventional tobacco cigarettes appear to have greater abuse liability than non-combusted products such as electronic cigarettes (ECs) and nicotine replacement therapy (NRT). This may be due to the higher levels of behaviorally active non-nicotine constituents [e.g., monoamine oxidase (MAO) inhibitors such as β-carbolines] in cigarette smoke (CS) compared to non-combusted products. To evaluate this hypothesis, the current studies compared the relative abuse liability of CS and EC aerosol extracts containing nicotine and a range of non-nicotine constituents to that of nicotine alone (NRT analog) using intracranial self-stimulation (ICSS) in rats. Effects of formulations on brain MAO activity in vitro and ex vivo were also studied to evaluate the potential role of MAO inhibition in the ICSS study. CS extract contained higher levels of several behaviorally active non-nicotine constituents (e.g., the β-carbolines norharmane and harmane) than EC extract. Nicotine alone reduced ICSS thresholds at a moderate nicotine dose, suggesting a reinforcement-enhancing effect that may promote abuse liability, and elevated ICSS thresholds at a high nicotine dose, suggesting an aversive/anhedonic effect that may limit abuse liability. CS extract elevated ICSS thresholds to a greater degree than nicotine alone at high nicotine doses. Effects of EC extract on ICSS did not differ from those of nicotine alone. Finally, CS extract significantly inhibited MAO-A and MAO-B activity in vitro, whereas EC extract and nicotine alone did not. None of the formulations inhibited MAO measured ex vivo. These findings indicate greater acute aversive/anhedonic effects for CS extract compared to nicotine alone, suggesting lower abuse liability. Although confirmation of our findings using other dosing regimens, preclinical addiction models, and tobacco product extracts is needed, these findings suggest that the centrally-mediated effects of MAO inhibitors and other non-nicotine constituents may not account for the greater abuse liability of cigarettes compared to non-combusted products. Nonetheless, identifying the specific constituent(s) mediating the effects of CS extracts in this study could help clarify mechanisms mediating tobacco addiction and inform FDA product standards.
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Affiliation(s)
- Andrew C. Harris
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States,Department of Medicine, University of Minnesota, Minneapolis, MN, United States,Department of Psychology, University of Minnesota, Minneapolis, MN, United States,*Correspondence: Andrew C. Harris,
| | - Peter Muelken
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States
| | - Aleksandra Alcheva
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, United States
| | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, United States
| | - Mark G. LeSage
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States,Department of Medicine, University of Minnesota, Minneapolis, MN, United States,Department of Psychology, University of Minnesota, Minneapolis, MN, United States
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3
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Levin ED, Wells C, Pace C, Abass G, Hawkey A, Holloway Z, Rezvani AH, Rose JE. Self-administration by female rats of low doses of nicotine alone vs. nicotine in tobacco smoke extract. Drug Alcohol Depend 2021; 228:109073. [PMID: 34600263 DOI: 10.1016/j.drugalcdep.2021.109073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Nicotine has reinforcing effects, but there are thousands of other compounds in tobacco, some of which might interact with nicotine reinforcement. AIMS This rat study was conducted to determine if nicotine self-administration is altered by co-administration of the complex mixture of compounds in tobacco smoke extract (TSE). METHODS Female Sprague-Dawley rats were tested for self-administration of low doses of nicotine (3 or 10 µg/kg/infusion) at three different rates of reinforcement (FR1, FR3 and FR5) over three weeks either alone or together with the complex mixture of tobacco smoke extract (TSE). RESULTS Rats self-administering 3 µg/kg/infusion of nicotine alone showed a rapid initiation on an FR1 schedule, but declined with FR5. Rats self-administering nicotine in TSE acquired self-administration more slowly, but increased responding over the course of the study. With 10 µg/kg/infusion rats self-administered significantly more nicotine alone than rats self-administering the same nicotine dose in TSE. Rats self-administering nicotine alone took significantly more infusions with the 10 than the 3 µg/kg/infusion dose, whereas rats self-administering nicotine in TSE did not. Nicotine in TSE led to a significantly greater locomotor hyperactivity at a dose of 0.1 mg/kg compared to rats that received nicotine alone. Rats self-administering nicotine alone had significantly more responding on the active vs. inactive lever, but rats self-administering the same nicotine doses in TSE did not. CONCLUSIONS Self-administration of nicotine in a purer form appears to be more clearly discriminated and dose-related than nicotine self-administered in the complex mixture of TSE.
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Affiliation(s)
- Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA.
| | - Corinne Wells
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Caroline Pace
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Grant Abass
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Andrew Hawkey
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Zade Holloway
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Amir H Rezvani
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Jed E Rose
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
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4
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Rahmadi M, Suasana D, Lailis SR, Ratri DMN, Ardianto C. The effects of quercetin on nicotine-induced reward effects in mice. J Basic Clin Physiol Pharmacol 2021; 32:327-333. [PMID: 34214359 DOI: 10.1515/jbcpp-2020-0418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/21/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Tobacco smoking remains the primary cause of preventable mortality and morbidity in the world. The complexity of the nicotine dependency process included the withdrawal effect that triggers recurrence being the main problem. Quercetin, known as an antioxidant, binds free radicals and modulates endogenous antioxidants through Nrf2 activations is expected as a potential agent to reduce the risk of nicotine dependence. This research aims to evaluate quercetin's effects on reducing the risk of nicotine addiction. METHODS Conditioned Place Preference (CPP) with a biased design was used to evaluate nicotine's reward effects in male Balb/C mice. Preconditioning test was performed on day 1; conditioning test was done twice daily on day 2-4 by administering quercetin (i.p.) 50 mg/kg along with nicotine (s.c.) 0.5 mg/kg or Cigarette Smoke Extract (CSE) (s.c.) contained nicotine 0.5 mg/kg; and postconditioning test was performed on day 5 continue with extinction test on day 6, 8, 10, 12, and reinstatement test on day 13. The duration spent in each compartment was recorded and analyzed. RESULTS Nicotine 0.5 mg/kg and CSE 0.5 mg/kg significantly induced reward effects (p<0.05). There was no decrease of reward effect during the extinction-reinstatement stage of the postconditioning phase (p>0.05), while quercetin 50 mg/kg both induced along with nicotine or CSE was able to inhibit the reward effect of nicotine (p>0.05). CONCLUSIONS Quercetin reduced the risk of nicotine dependence and has a potential effect to use as a therapy for nicotine dependence, especially as a preventive agent.
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Affiliation(s)
- Mahardian Rahmadi
- Department of Clinical Pharmacy, Faculty of Pharmacy, University of Airlangga, Surabaya, Indonesia
| | - Dian Suasana
- Department of Clinical Pharmacy, Faculty of Pharmacy, University of Airlangga, Surabaya, Indonesia
| | - Silvy Restuning Lailis
- Department of Clinical Pharmacy, Faculty of Pharmacy, University of Airlangga, Surabaya, Indonesia
| | | | - Chrismawan Ardianto
- Department of Clinical Pharmacy, Faculty of Pharmacy, University of Airlangga, Surabaya, Indonesia
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5
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Sex- and age-dependent differences in nicotine susceptibility evoked by developmental exposure to tobacco smoke and/or ethanol in mice. J Dev Orig Health Dis 2020; 12:940-951. [PMID: 33292889 DOI: 10.1017/s2040174420001191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Either tobacco smoking or alcohol consumption during pregnancy sex-selectively increases susceptibility to drugs of abuse later in life. Considering that pregnant smoking women are frequently intermittent consumers of alcoholic beverages, here, we investigated whether a short-term ethanol exposure restricted to the brain growth spurt period when combined with chronic developmental exposure to tobacco smoke aggravates susceptibility to nicotine in adolescent and adult mice. Swiss male and female mice were exposed to tobacco smoke (SMK; research cigarettes 3R4F, whole-body exposure, 8 h/daily) or ambient air during the gestational period and until the tenth postnatal day (PN). Ethanol (ETOH, 2 g/Kg, 25%, i.p.) or saline was injected in the pups every other day from PN2 to PN10. There were no significant differences in cotinine (nicotine metabolite) and ethanol serum levels among SMK, ETOH and SMK + ETOH groups. During adolescence (PN30) and adulthood (PN90), nicotine (NIC, 0.5 mg/Kg) susceptibility was evaluated in the conditioned place preference and open field tests. NIC impact was more evident in females: SMK, ETOH and SMK + ETOH adolescent females were equally more susceptible to nicotine-induced place preference than control animals. At adulthood, SMK and SMK + ETOH adult females exhibited a nicotine-evoked hyperlocomotor profile in the open field, with a stronger effect in the SMK + ETOH group. Our results indicate that ethanol exposure during the brain growth spurt, when combined to developmental exposure to tobacco smoke, increases nicotine susceptibility with stronger effects in adult females. This result represents a worsened outcome from the early developmental dual exposure and may predispose nicotine use/abuse later in life.
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Comparison of the Relative Abuse Liability of Electronic Cigarette Aerosol Extracts and Nicotine Alone in Adolescent Rats: A Behavioral Economic Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030860. [PMID: 32019080 PMCID: PMC7037300 DOI: 10.3390/ijerph17030860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 12/02/2022]
Abstract
Background: Characterizing the determinants of the abuse liability of electronic cigarettes (ECs) in adolescents is needed to inform product regulation by the United States Food and Drug Administration (FDA). We recently reported that Vuse Menthol EC aerosol extract containing nicotine and a range of non-nicotine constituents (e.g., menthol, propylene glycol) had reduced aversive effects compared to nicotine alone in adolescent rats, whereas Aroma E-Juice EC aerosol extract did not. The current study used a behavioral economic approach to compare the relative abuse liability of these EC extracts and nicotine alone in an i.v. self-administration (SA) model in adolescents. Methods: Adolescents were tested for the SA of EC extracts prepared using an ethanol (ETOH) solvent or nicotine and saline, with and without 4% ETOH (i.e., the same concentration in the EC extracts) in 23 h/day sessions. Results. Although acquisition of SA was faster for nicotine + ETOH compared to all other formulations, the elasticity of demand for all nicotine-containing formulations was similar. Conclusions: EC aerosol extracts did not have greater abuse liability than nicotine alone in adolescents. These data suggest that nicotine may be the primary determinant of the abuse liability of these ECs in youth, at least in terms of the primary reinforcing effects of ECs mediated within the central nervous system.
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7
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Harris AC, Muelken P, Swain Y, Palumbo M, Jain V, Goniewicz ML, Stepanov I, LeSage MG. Non-nicotine constituents in e-cigarette aerosol extract attenuate nicotine's aversive effects in adolescent rats. Drug Alcohol Depend 2019; 203:51-60. [PMID: 31404849 PMCID: PMC6941564 DOI: 10.1016/j.drugalcdep.2019.05.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 01/05/2023]
Abstract
BACKGROUND Development of preclinical methodology for evaluating the abuse liability of electronic cigarettes (ECs) in adolescents is urgently needed to inform FDA regulation of these products. We previously reported reduced aversive effects of EC liquids containing nicotine and a range of non-nicotine constituents (e.g., propylene glycol, minor tobacco alkaloids) compared to nicotine alone in adult rats as measured using intracranial self-stimulation. The goal of this study was to compare the aversive effects of nicotine alone and EC aerosol extracts in adolescent rats as measured using conditioned taste aversion (CTA), which can be conducted during the brief adolescent period. METHODS AND RESULTS In Experiment 1, nicotine alone (1.0 or 1.5 mg/kg, s.c.) produced significant CTA in adolescent rats in a two-bottle procedure, thereby establishing a model to study the effects of EC extracts. At a nicotine dose of 1.0 mg/kg, CTA to Vuse Menthol EC extract, but not Aroma E-Juice EC extract, was attenuated compared to nicotine alone during repeated two-bottle CTA tests (Experiment 2a). At a nicotine dose of 0.5 mg/kg, CTA to Vuse Menthol EC extract did not differ from nicotine alone during the first two-bottle CTA test but extinguished more rapidly across repeated two-bottle tests (Experiment 2b). CONCLUSIONS Non-nicotine constituents in Vuse Menthol EC extracts attenuated CTA in a two-bottle procedure in adolescents. This model may be useful for anticipating the abuse liability of ECs in adolescents and for modeling FDA-mandated changes in product standards for nicotine or other constituents in ECs.
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Affiliation(s)
- Andrew C. Harris
- Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA,Department of Medicine, University of Minnesota, Minneapolis, MN, USA,Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - Peter Muelken
- Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA
| | - Yayi Swain
- Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA,Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - Mary Palumbo
- Department of Health Behavior, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Vipin Jain
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Maciej L. Goniewicz
- Department of Health Behavior, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Mark G. LeSage
- Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA,Department of Medicine, University of Minnesota, Minneapolis, MN, USA,Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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8
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LeSage MG, Smethells JR, Harris AC. Status and Future Directions of Preclinical Behavioral Pharmacology in Tobacco Regulatory Science. ACTA ACUST UNITED AC 2018; 18:252-274. [PMID: 30214916 DOI: 10.1037/bar0000113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Behavioral pharmacology is a branch of the experimental analysis of behavior that has had great influence in drug addiction research and policy. This paper provides an overview of recent behavioral pharmacology research in the field of tobacco regulatory science, which provides the scientific foundation for the Food and Drug Administration Center for Tobacco Products (FDA CTP) to set tobacco control policies. The rationale and aims of tobacco regulatory science are provided, including the types of preclinical operant behavioral models it deems important for assessing the abuse liability of tobacco products and their constituents. We then review literature relevant to key regulatory actions being considered by the FDA CTP, including regulations over nicotine and menthol content of cigarettes, and conclude with suggesting some directions for future research. The current era of tobacco regulatory science provides great opportunities for behavioral pharmacologists to address the leading cause of preventable death and disease worldwide.
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Affiliation(s)
- Mark G LeSage
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
- Department of Psychology, University of Minnesota
| | - John R Smethells
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
| | - Andrew C Harris
- Department of Medicine, Minneapolis Medical Research Foundation
- Departments of Medicine, University of Minnesota
- Department of Psychology, University of Minnesota
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9
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Smith TT, Rupprecht LE, Denlinger-Apte RL, Weeks JJ, Panas RS, Donny EC, Sved AF. Animal Research on Nicotine Reduction: Current Evidence and Research Gaps. Nicotine Tob Res 2018; 19:1005-1015. [PMID: 28379511 DOI: 10.1093/ntr/ntx077] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 03/31/2017] [Indexed: 01/21/2023]
Abstract
A mandated reduction in the nicotine content of cigarettes may improve public health by reducing the prevalence of smoking. Animal self-administration research is an important complement to clinical research on nicotine reduction. It can fill research gaps that may be difficult to address with clinical research, guide clinical researchers about variables that are likely to be important in their own research, and provide policy makers with converging evidence between clinical and preclinical studies about the potential impact of a nicotine reduction policy. Convergence between clinical and preclinical research is important, given the ease with which clinical trial participants can access nonstudy tobacco products in the current marketplace. Herein, we review contributions of preclinical animal research, with a focus on rodent self-administration, to the science of nicotine reduction. Throughout this review, we highlight areas where clinical and preclinical research converge and areas where the two differ. Preclinical research has provided data on many important topics such as the threshold for nicotine reinforcement, the likelihood of compensation, moderators of the impact of nicotine reduction, the impact of environmental stimuli on nicotine reduction, the impact of nonnicotine cigarette smoke constituents on nicotine reduction, and the impact of nicotine reduction on vulnerable populations. Special attention is paid to current research gaps including the dramatic rise in alternative tobacco products, including electronic nicotine delivery systems (ie, e-cigarettes). The evidence reviewed here will be critical for policy makers as well as clinical researchers interested in nicotine reduction. IMPLICATIONS This review will provide policy makers and clinical researchers interested in nicotine reduction with an overview of the preclinical animal research conducted on nicotine reduction and the regulatory implications of that research. The review also highlights the utility of preclinical research for research questions related to nicotine reduction.
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Affiliation(s)
- Tracy T Smith
- University of Pittsburgh Cancer Institute, Pittsburgh, PA.,Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA
| | - Laura E Rupprecht
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Rachel L Denlinger-Apte
- Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, RI
| | - Jillian J Weeks
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Rachel S Panas
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA
| | - Alan F Sved
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA.,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
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10
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Truman P, Grounds P, Brennan KA. Monoamine oxidase inhibitory activity in tobacco particulate matter: Are harman and norharman the only physiologically relevant inhibitors? Neurotoxicology 2017; 59:22-26. [PMID: 28057462 DOI: 10.1016/j.neuro.2016.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/14/2016] [Accepted: 12/31/2016] [Indexed: 10/20/2022]
Abstract
Monoamine oxidase inhibition is significant in smokers, but it is still unclear how the inhibition that is seen in the brains and bodies of smokers is brought about. Our aim was to test the contribution of the harman and norharman in tobacco smoke to MAO-A inhibition from tobacco smoke preparations, as part of a re-examination of harman and norharman as the cause of the inhibition of MAO-A inhibition in the brain. Tobacco smoke particulate matter and cigarette smoke particulate matter were prepared and the amounts of harman and norharman measured. The results were compared with the total monoamine oxidase-A inhibitory activity. At a nicotine concentration of 0.6μM (a "physiological" concentration in blood) the total monoamine oxidase-A inhibitory activity measured in these samples was sufficient to inhibit the enzyme by approximately 10%. Of this inhibitory activity, only a small proportion of the total was found to be due to harman and norharman. These results show that harman and norharman provide only a moderate contribution to the total monoamine oxidase-A inhibitory activity of tobacco smoke, perhaps under 10%. This suggests that other inhibitors (either known or unknown) may be more significant contributors to total inhibitory activity than has yet been established, and deserve closer examination.
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Affiliation(s)
- Penelope Truman
- Institute of Environmental Science and Research Ltd, Porirua, New Zealand; Massey University, Wellington, New Zealand.
| | - Peter Grounds
- Institute of Environmental Science and Research Ltd, Christchurch, New Zealand
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11
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Henningfield JE, Smith TT, Kleykamp BA, Fant RV, Donny EC. Nicotine self-administration research: the legacy of Steven R. Goldberg and implications for regulation, health policy, and research. Psychopharmacology (Berl) 2016; 233:3829-3848. [PMID: 27766371 PMCID: PMC5588156 DOI: 10.1007/s00213-016-4441-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 09/15/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND RATIONALE Steven R. Goldberg was a pioneering behavioral pharmacologist whose intravenous drug self-administration studies advanced the understanding of conditioned stimuli and schedules of reinforcement as determinants of pattern and persistence of drug-seeking behavior, and in particular, the importance of nicotine in tobacco use. His passing in 2014 led to invitations to contribute articles to psychopharmacology dedicated to his work. OBJECTIVES The objectives of this review are to summarize and put into historical perspective Goldberg's contributions to elucidate the reinforcing effects of nicotine and to summarize the implications of his research for medication development, tobacco regulation, and potential tobacco control policy options. This includes a review of intravenous nicotine self-administration research from the 1960s to 2016. RESULTS Goldberg's application of behavioral pharmacology methods to investigate nicotine reinforcement and the influence of schedule of reinforcement and conditioned stimuli on nicotine administration contributed to the conclusions of the US National Institute on Drug Abuse, and the Surgeon General, that nicotine met the criteria as a dependence-producing drug and cigarette smoking as a prototypic drug dependency or "addiction." Equally important, this work has been systematically extended to other species and applied to address a range of factors relevant to tobacco use, medication development, regulation, and public health policy. CONCLUSIONS Steven R. Goldberg was a pioneering scientist whose systematic application of the science of behavioral pharmacology advanced the understanding of tobacco and nicotine use and contributed to the scientific foundation for tobacco product regulation and potential public health tobacco control policy development.
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Affiliation(s)
- Jack E Henningfield
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA.
- Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Tracy T Smith
- University of Pittsburgh Cancer Institute, 4120 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 4120 Sennott Square, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
| | - Bethea A Kleykamp
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA
| | - Reginald V Fant
- Pinney Associates, 4800 Montgomery Lane, Suite 400, Bethesda, MD, 20814, USA
| | - Eric C Donny
- Department of Psychology, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA, 15260, USA
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12
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LeSage MG, Staley M, Muelken P, Smethells JR, Stepanov I, Vogel RI, Pentel PR, Harris AC. Abuse liability assessment of an e-cigarette refill liquid using intracranial self-stimulation and self-administration models in rats. Drug Alcohol Depend 2016; 168:76-88. [PMID: 27627814 PMCID: PMC5257285 DOI: 10.1016/j.drugalcdep.2016.08.628] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/14/2016] [Accepted: 08/22/2016] [Indexed: 01/19/2023]
Abstract
BACKGROUND The popularity of electronic cigarettes (ECs) has increased dramatically despite their unknown health consequences. Because the abuse liability of ECs is one of the leading concerns of the Food and Drug Administration (FDA), models to assess it are urgently needed to inform FDA regulatory decisions regarding these products. The purpose of this study was to assess the relative abuse liability of an EC liquid compared to nicotine alone in rats. Because this EC liquid contains non-nicotine constituents that may enhance its abuse liability, we hypothesized that it would have greater abuse liability than nicotine alone. METHODS Nicotine alone and nicotine dose-equivalent concentrations of EC liquid were compared in terms of their acute effects on intracranial self-stimulation (ICSS) thresholds, acquisition of self-administration, reinforcing efficacy (i.e., elasticity of demand), blockade of these behavioral effects by mecamylamine, nicotine pharmacokinetics and nicotinic acetylcholine receptor binding and activation. RESULTS There were no significant differences between formulations on any measure, except that EC liquid produced less of an elevation in ICSS thresholds at high nicotine doses. CONCLUSIONS Collectively, these findings suggest that the relative abuse liability of this EC liquid is similar to that of nicotine alone in terms of its reinforcing and reinforcement-enhancing effects, but that it may have less aversive/anhedonic effects at high doses. The present methods may be useful for assessing the abuse liability of other ECs to inform potential FDA regulation of those products.
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Affiliation(s)
- MG LeSage
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN,Department of Psychology, University of Minnesota, Minneapolis, MN, 55455
| | - M Staley
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN
| | - P Muelken
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN
| | - JR Smethells
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Psychiatry, University of Minnesota, Minneapolis, MN, 55455
| | - I Stepanov
- Masonic Cancer, Center University of Minnesota, Minneapolis, MN
| | - RI Vogel
- Masonic Cancer Center Biostatistics and Bioinformatics Core ,University of Minnesota Minneapolis, MN
| | - PR Pentel
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN
| | - AC Harris
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN,Department of Medicine, University of Minnesota, Minneapolis, MN,Department of Psychology, University of Minnesota, Minneapolis, MN, 55455
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13
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Gomez R, Schneider R, Quinteros D, Santos CF, Bandiera S, Thiesen FV, Coitinho AS, Fernandes MDC, Wieczorek MG. Effect of Alcohol and Tobacco Smoke on Long-Term Memory and Cell Proliferation in the Hippocampus of Rats. Nicotine Tob Res 2015; 17:1442-8. [PMID: 25744965 DOI: 10.1093/ntr/ntv051] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 02/19/2015] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Alcohol is frequently used in combination with tobacco and few studies explore interactions between these two drugs of abuse. Here, we evaluated the effect of chronic alcohol administration and concomitant exposure to tobacco smoke on long-term memory and on cell proliferation in the hippocampus of rats. METHODS Forty male Wistar rats were assigned to four groups and treated with alcohol (2g/kg by gavage) and/or exposed to tobacco smoke (from six cigarettes, by inhalation) twice a day (at 9:00 AM and 2:00 PM) for 30 days. Long-term memory was evaluated in the inhibitory avoidance test and hippocampal cell proliferation was analyzed for bromodeoxyuridine immunohistochemistry. RESULTS Our results showed that alcohol, tobacco smoke, or their combination improved the long-term memory evaluated by the memory index in rats. Moreover, alcohol and tobacco coadministration decreased bromodeoxyuridine-labeled cells by 60% when compared to the control group, while alcohol treatment decreased labeled cells by 40%. The tobacco group showed a nonsignificant 26% decrease in labeled cells compared to the control group. CONCLUSIONS Chronic alcohol and tobacco coadministration improves the long-term memory in rats in the inhibitory avoidance test. However, coadministration decreases the cell proliferation in the hippocampus of rats, suggesting a deleterious effect by the combined use of these drugs of abuse.
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Affiliation(s)
- Rosane Gomez
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil; Programa de Pós-Graduação em Ciências Biológicas: Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil;
| | - Ricardo Schneider
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil; Programa de Pós-Graduação em Ciências Biológicas: Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Dayane Quinteros
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Carolina Ferreira Santos
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Solange Bandiera
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Flavia Valadão Thiesen
- Departamento de Toxicologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brasil
| | - Adriana Simon Coitinho
- Departamento de Microbiologia e Imunologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Marilda da Cruz Fernandes
- Laboratório de Patologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brasil
| | - Marina Godinho Wieczorek
- Laboratório de Álcool e Tabaco, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
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14
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Smith TT, Schaff MB, Rupprecht LE, Schassburger RL, Buffalari DM, Murphy SE, Sved AF, Donny EC. Effects of MAO inhibition and a combination of minor alkaloids, β-carbolines, and acetaldehyde on nicotine self-administration in adult male rats. Drug Alcohol Depend 2015; 155:243-52. [PMID: 26257022 PMCID: PMC4581969 DOI: 10.1016/j.drugalcdep.2015.07.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 07/02/2015] [Accepted: 07/02/2015] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Although nicotine is the primary reinforcing constituent in cigarettes, there is evidence that other constituents in cigarette smoke may interact with nicotine to reinforce smoking behavior. METHODS The present experiments investigated whether a novel combination of these cigarette smoke constituents would increase nicotine self-administration in adult male rats. The constituents included five minor alkaloids (anabasine, nornicotine, cotinine, myosmine, and anatabine), two β-carbolines (harman and norharman), and acetaldehyde. All doses were indexed to be proportional to concentrations in cigarette smoke given a standard dose of nicotine used in rodent self-administration, or ten times higher than this standard. To model MAO inhibition seen in chronic smokers, some groups received separate injections of tranylcypromine prior to each self-administration session. RESULTS Tranylcypromine increased low-dose nicotine self-administration independent of other smoke constituents, which had no effect on self-administration behavior. The effect of tranylcypromine was confirmed across a large range of reinforcement schedules. The effect of tranylcypromine on low-dose nicotine self-administration was observed regardless of whether the injection was delivered 1-h or 23-h prior to the self-administration session, consistent with the interpretation that MAO inhibition was responsible for the increase in self-administration, instead of acute off-target effects. CONCLUSIONS These data suggest that this cocktail of constituents does not significantly alter the primary reinforcing effects of nicotine, but constituents that inhibit MAO may increase the primary reinforcing effects of nicotine, especially at low doses.
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15
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Abreu-Villaça Y, Filgueiras CC, Correa-Santos M, Cavina CC, Naiff VF, Krahe TE, Manhães AC, Ribeiro-Carvalho A. Tobacco smoke containing high or low levels of nicotine during adolescence: effects on novelty-seeking and anxiety-like behaviors in mice. Psychopharmacology (Berl) 2015; 232:1693-703. [PMID: 25401170 DOI: 10.1007/s00213-014-3801-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 10/31/2014] [Indexed: 01/11/2023]
Abstract
RATIONALE Thousands of adolescents start smoking daily but information on the effects of tobacco exposure on this age group is scarce. Moreover, the available animal models rely on the effects of nicotine, neglecting other neuroactive components of tobacco. OBJECTIVES We investigated the effects of exposure of adolescent mice to tobacco smoke generated from cigarettes containing either high or low levels of nicotine on novelty seeking and anxiety-like behaviors. METHODS From postnatal day (PN) 30 to 45, male and female Swiss mice were exposed to tobacco smoke (whole body exposure, 8 h/day, 7 days/week) generated from 2R1F (HighNic group: 1.74 mg nicotine/cigarette) or 4A1 (LowNic group: 0.14 mg nicotine/cigarette) research cigarettes, whereas control mice were exposed to ambient air. By the end (PN44-45), shortly (PN49-50), or long after (PN74-75) exposure, mice were tested on the elevated plus maze and on the hole board. RESULTS While HighNic mice presented an increased number of head-dips (increased novelty-seeking) and decreased grooming (increased anxiety-like behavior) by the end of adolescent exposure, only the latter effect persisted shortly after its end. Distinctively, LowNic mice presented reduced head-dips both by the end and shortly after exposure as well as decreased grooming shortly and long after the end of exposure. Interestingly, only HighNic mice presented detectable cotinine (nicotine metabolite) serum levels (109.1 ± 24.0 ng/ml). CONCLUSION Our results demonstrate that even adolescent exposure to tobacco smoke with very low nicotine content can have significant short- and long-term behavioral effects, supporting the hypothesis that adolescents can be particularly vulnerable to the effects of cigarette consumption.
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Affiliation(s)
- Yael Abreu-Villaça
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro (UERJ), Av. Prof. Manuel de Abreu 444, 5 andar - Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil,
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16
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Harris AC, Tally L, Schmidt CE, Muelken P, Stepanov I, Saha S, Vogel RI, LeSage MG. Animal models to assess the abuse liability of tobacco products: effects of smokeless tobacco extracts on intracranial self-stimulation. Drug Alcohol Depend 2015; 147:60-7. [PMID: 25561387 PMCID: PMC4337227 DOI: 10.1016/j.drugalcdep.2014.12.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/12/2014] [Accepted: 12/11/2014] [Indexed: 01/11/2023]
Abstract
BACKGROUND Preclinical models are needed to inform regulation of tobacco products by the Food and Drug Administration (FDA). Typically, animal models of tobacco addiction involve exposure to nicotine alone or nicotine combined with isolated tobacco constituents (e.g. minor alkaloids). The goal of this study was to develop a model using extracts derived from tobacco products that contain a range of tobacco constituents to more closely model product exposure in humans. METHODS This study compared the addiction-related effects of nicotine alone and nicotine dose-equivalent concentrations of aqueous smokeless tobacco extracts on intracranial self-stimulation (ICSS) in rats. Extracts were prepared from Kodiak Wintergreen, a conventional product, or Camel Snus, a potential "modified risk tobacco product". Binding affinities of nicotine alone and extracts at various nicotinic acetylcholine receptor (nAChR) subtypes were also compared. RESULTS Kodiak and Camel Snus extracts contained levels of minor alkaloids within the range of those shown to enhance nicotine's behavioral effects when studied in isolation. Nonetheless, acute injection of both extracts produced reinforcement-enhancing (ICSS threshold-decreasing) effects similar to those of nicotine alone at low to moderate nicotine doses, as well as similar reinforcement-attenuating/aversive (ICSS threshold-increasing) effects at high nicotine doses. Extracts and nicotine alone also had similar binding affinity at all nAChRs studied. CONCLUSIONS Relative nicotine content is the primary pharmacological determinant of the abuse liability of Kodiak and Camel Snus as measured using ICSS. These models may be useful to compare the relative abuse liability of other tobacco products and to model FDA-mandated changes in product performance standards.
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Affiliation(s)
- Andrew C Harris
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA.
| | - Laura Tally
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA
| | - Clare E Schmidt
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Peter Muelken
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Ecology, Evolution, and Behavior, University of Minnesota, Minneapolis, MN, USA
| | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Subhrakanti Saha
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Rachel Isaksson Vogel
- Masonic Cancer Center, Biostatistics and Bioinformatics Core, University of Minnesota Minneapolis, MN, USA
| | - Mark G LeSage
- Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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17
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Brennan KA, Laugesen M, Truman P. Whole tobacco smoke extracts to model tobacco dependence in animals. Neurosci Biobehav Rev 2014; 47:53-69. [PMID: 25064817 DOI: 10.1016/j.neubiorev.2014.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/12/2014] [Accepted: 07/14/2014] [Indexed: 01/01/2023]
Abstract
Smoking tobacco is highly addictive and a leading preventable cause of death. The main addictive constituent is nicotine; consequently it has been administered to laboratory animals to model tobacco dependence. Despite extensive use, this model might not best reflect the powerful nature of tobacco dependence because nicotine is a weak reinforcer, the pharmacology of smoke is complex and non-pharmacological factors have a critical role. These limitations have led researchers to expose animals to smoke via the inhalative route, or to administer aqueous smoke extracts to produce more representative models. The aim was to review the findings from molecular/behavioural studies comparing the effects of nicotine to tobacco/smoke extracts to determine whether the extracts produce a distinct model. Indeed, nicotine and tobacco extracts yielded differential effects, supporting the initiative to use extracts as a complement to nicotine. Of the behavioural tests, intravenous self-administration experiments most clearly revealed behavioural differences between nicotine and extracts. Thus, future applications for use of this behavioural model were proposed that could offer new insights into tobacco dependence.
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Affiliation(s)
- Katharine A Brennan
- School of Psychology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
| | - Murray Laugesen
- Health New Zealand Ltd, 36 Winchester St, Lyttelton, Christchurch, New Zealand
| | - Penelope Truman
- Institute of Environmental Science and Research Ltd, PO Box 50348, Porirua 5240, New Zealand
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18
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Costello MR, Reynaga DD, Mojica CY, Zaveri NT, Belluzzi JD, Leslie FM. Comparison of the reinforcing properties of nicotine and cigarette smoke extract in rats. Neuropsychopharmacology 2014; 39:1843-51. [PMID: 24513971 PMCID: PMC4059892 DOI: 10.1038/npp.2014.31] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/03/2014] [Accepted: 01/23/2014] [Indexed: 12/27/2022]
Abstract
Tobacco dependence is difficult to treat, with the vast majority of those who try to quit relapsing within the first year. Improvements in smoking cessation therapies may be achieved by improving current preclinical research methods. However, most experimental tests in animals use nicotine alone, ignoring the 8000 other constituents found in tobacco smoke. To improve on this model, we have used self-administration to test the reinforcing properties of aqueous cigarette smoke extract (CSE) in rats, made by bubbling cigarette smoke through a saline solution. CSE is more potent than nicotine alone in both the acquisition and maintenance of self-administration, but did not exhibit higher progressive ratio responding. Mecamylamine and varenicline had similar potencies to block nicotine and CSE self-administration, indicating the involvement of nicotinic receptors in CSE reinforcement. Following extinction of responding, reinstatement was triggered by exposing animals to a pharmacological stressor, yohimbine (2.5 mg/kg, i.p.), alone and in combination with cues. Animals that self-administered CSE were significantly more sensitive to stress-induced reinstatement than those that self-administered nicotine. Ligand binding autoradiography studies showed nicotine and CSE to have similar affinities for different nicotinic receptor types. CSE significantly reduced MAO-A and MAO-B activities in vitro, whereas nicotine did not. Although CSE inhibition of MAO-A activity in vitro was found to be partially irreversible, irreversible inhibition was not observed in vivo. These experiments show that CSE is an effective reinforcer acting via nicotinic receptors. Furthermore, it better models MAO inhibition and is more sensitive to stress-induced reinstatement than nicotine alone, which is a potent trigger for relapse in smokers.
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Affiliation(s)
- Matthew R Costello
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA, USA
| | - Daisy D Reynaga
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA, USA
| | - Celina Y Mojica
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA, USA
| | | | - James D Belluzzi
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA, USA
| | - Frances M Leslie
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA, USA
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19
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Elrashidi MY, Ebbert JO. Emerging drugs for the treatment of tobacco dependence: 2014 update. Expert Opin Emerg Drugs 2014; 19:243-60. [PMID: 24654737 DOI: 10.1517/14728214.2014.899580] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Tobacco dependence remains a global epidemic and the largest preventable cause of morbidity and mortality around the world. Smoking cessation has benefits at all ages but remains challenging for several reasons, among which are the complexities of nicotine addiction and limitations of available pharmacotherapies. AREAS COVERED This review summarizes current and emerging pharmacotherapies for the treatment of tobacco dependence, including first- and second-line recommended agents. Medications with alternative primary indications that have been investigated as potential treatments for tobacco dependence are also discussed. Articles reviewed were obtained through searches of PubMed, Ovid MEDLINE, ClinicalTrials.gov and the Pharmaprojects database. EXPERT OPINION Current evidence suggests that the two most effective pharmacotherapies to treat tobacco dependence are varenicline and combination nicotine replacement therapy. Alternative agents investigated demonstrate mixed rates of success in achieving long-term abstinence from smoking. No single pharmacotherapy will serve as a universally successful treatment given the complex underpinnings of tobacco dependence and individuality of smokers. The ultimate goal of tobacco research with respect to pharmacotherapeutic development continues to be providing clinicians with an armamentarium of drugs to choose from allowing for tailoring of treatment for smokers.
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