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Magliaro C, Ahluwalia A. Biomedical Research on Substances of Abuse: The Italian Case Study. Altern Lab Anim 2022; 50:423-436. [PMID: 36222242 DOI: 10.1177/02611929221132215] [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: 11/17/2022]
Abstract
Substances of abuse have the potential to cause addiction, habituation or altered consciousness. Most of the research on these substances focuses on addiction, and is carried out through observational and clinical studies on humans, or experimental studies on animals. The transposition of the EU Directive 2010/63 into Italian law in 2014 (IT Law 2014/26) includes a ban on the use of animals for research on substances of abuse. Since then, in Italy, public debate has continued on the topic, while the application of the Article prohibiting animal research in this area has been postponed every couple of years. In the light of this debate, we briefly review a range of methodologies - including animal and non-animal, as well as patient or population-based studies - that have been employed to address the biochemical, neurobiological, toxicological, clinical and behavioural effects of substances of abuse and their dependency. We then discuss the implications of the Italian ban on the use of animals for such research, proposing concrete and evidence-based solutions to allow scientists to pursue high-quality basic and translational studies within the boundaries of the regulatory and legislative framework.
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Affiliation(s)
- Chiara Magliaro
- Research Centre 'E. Piaggio', 9310University of Pisa, Pisa, Italy.,Department of Information Engineering, 9310University of Pisa, Pisa, Italy.,Interuniversity Centre for the Promotion of 3R Principles in Teaching and Research (Centro 3R), Pisa, Italy
| | - Arti Ahluwalia
- Research Centre 'E. Piaggio', 9310University of Pisa, Pisa, Italy.,Department of Information Engineering, 9310University of Pisa, Pisa, Italy.,Interuniversity Centre for the Promotion of 3R Principles in Teaching and Research (Centro 3R), Pisa, Italy
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2
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Havermans A, Mallock N, Zervas E, Caillé-Garnier S, Mansuy T, Michel C, Pennings JLA, Schulz T, Schwarze PE, Solimini R, Tassin JP, Vardavas CI, Merino M, Pauwels CGGM, van Nierop LE, Lambré C, Bolling AK. Review of industry reports on EU priority tobacco additives part A: Main outcomes and conclusions. Tob Prev Cessat 2022; 8:27. [PMID: 35860504 PMCID: PMC9255285 DOI: 10.18332/tpc/151529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/21/2022] [Accepted: 06/24/2022] [Indexed: 02/01/2023]
Abstract
The European Union Tobacco Products Directive (EU TPD) mandates enhanced reporting obligations for tobacco manufacturers regarding 15 priority additives. Within the Joint Action on Tobacco Control (JATC), a review panel of independent experts was appointed for the scientific evaluation of the additive reports submitted by a consortium of 12 tobacco manufacturers. As required by the TPD, the reports were evaluated based on their comprehensiveness, methodology and conclusions. In addition, we evaluated the chemical, toxicological, addictive, inhalation facilitating and flavoring properties of the priority additives based on the submitted reports, supplemented by the panel's expert knowledge and some independent literature. The industry concluded that none of the additives is associated with concern. Due to significant methodological limitations, we question the scientific validity of these conclusions and conclude that they are not warranted. Our review demonstrates that many issues regarding toxicity, addictiveness and attractiveness of the additives have not been sufficiently addressed, and therefore concerns remain. For example, menthol facilitates inhalation by activation of the cooling receptor TRPM8. The addition of sorbitol and guar gum leads to a significant increase of aldehydes that may contribute to toxicity and addictiveness. Titanium dioxide particles (aerodynamic diameter <10 µm) are legally classified as carcinogenic when inhaled. For diacetyl no report was provided. Overall, the industry reports were not comprehensive, and the information presented provides an insufficient basis for the regulation of most additives. We, therefore, advise MS to consider alternative approaches such as the precautionary principle.
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Affiliation(s)
- Anne Havermans
- Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | - Nadja Mallock
- German Federal Institute for Risk Assessment, Berlin, Germany
| | - Efthimios Zervas
- Hellenic Thoracic Society, Athens, Greece.,School of Applied Arts and Sustainable Design, Hellenic Open University, Athens, Greece
| | | | - Thibault Mansuy
- French Agency for Food, Environmental and Occupational Health and Safety, Paris, France
| | - Cécile Michel
- French Agency for Food, Environmental and Occupational Health and Safety, Paris, France
| | - Jeroen L A Pennings
- Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | - Thomas Schulz
- German Federal Institute for Risk Assessment, Berlin, Germany
| | | | | | | | | | - Miguel Merino
- Andalusia Agency For Agriculture and Fisheries Development, Seville, Spain
| | - Charlotte G G M Pauwels
- Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | - Lotte E van Nierop
- Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, Netherlands
| | - Claude Lambré
- National Institute of Health and Medical Research, Paris, France
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Johnson NL, Patten T, Ma M, De Biasi M, Wesson DW. Chemosensory Contributions of E-Cigarette Additives on Nicotine Use. Front Neurosci 2022; 16:893587. [PMID: 35928010 PMCID: PMC9344001 DOI: 10.3389/fnins.2022.893587] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
While rates of smoking combustible cigarettes in the United States have trended down in recent years, use of electronic cigarettes (e-cigarettes) has dramatically increased, especially among adolescents. The vast majority of e-cigarette users consume "flavored" products that contain a variety of chemosensory-rich additives, and recent literature suggests that these additives have led to the current "teen vaping epidemic." This review, covering research from both human and rodent models, provides a comprehensive overview of the sensory implications of e-cigarette additives and what is currently known about their impact on nicotine use. In doing so, we specifically address the oronasal sensory contributions of e-cigarette additives. Finally, we summarize the existing gaps in the field and highlight future directions needed to better understand the powerful influence of these additives on nicotine use.
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Affiliation(s)
- Natalie L. Johnson
- Department of Pharmacology and Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, University of Florida, Gainesville, FL, United States
| | - Theresa Patten
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Minghong Ma
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Mariella De Biasi
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Daniel W. Wesson
- Department of Pharmacology and Therapeutics, Center for Smell and Taste, Center for Addiction Research and Education, University of Florida, Gainesville, FL, United States
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Bagdas D, Kebede N, Zepei AM, Harris L, Minanov K, Picciotto MR, Addy NA. Animal Models to Investigate the Impact of Flavors on Nicotine Addiction and Dependence. Curr Neuropharmacol 2022; 20:2175-2201. [PMID: 35611777 PMCID: PMC9886843 DOI: 10.2174/1570159x20666220524120231] [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] [Received: 12/26/2021] [Revised: 04/17/2022] [Accepted: 05/22/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Tobacco use in humans is a long-standing public health concern. Flavors are common additives in tobacco and alternative tobacco products, added to mask nicotine's harsh orosensory effects and increase the appeal of these products. Animal models are integral for investigating nicotine use and addiction and are helpful for understanding the effects of flavor additives on the use of nicotine delivery products. OBJECTIVE This review focuses on preclinical models to evaluate the contribution of flavor additives to nicotine addiction. MATERIALS AND METHODS An electronic literature search was conducted by authors up to May 2022. Original articles were selected. RESULTS The behavioral models of rodents described here capture multiple dimensions of human flavored nicotine use behaviors, including advantages and disadvantages. CONCLUSION The consensus of the literature search was that human research on nicotine use behavior has not caught up with fast-changing product innovations, marketing practices, and federal regulations. Animal models are therefore needed to investigate mechanisms underlying nicotine use and addiction. This review provides a comprehensive overvie.
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Affiliation(s)
- Deniz Bagdas
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Yale Tobacco Center of Regulatory Science, Yale School of Medicine, New Haven, CT, USA
| | - Nardos Kebede
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Andy Ma Zepei
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Lilley Harris
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Karina Minanov
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Marina R. Picciotto
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Yale Tobacco Center of Regulatory Science, Yale School of Medicine, New Haven, CT, USA
| | - Nii A. Addy
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Yale Tobacco Center of Regulatory Science, Yale School of Medicine, New Haven, CT, USA
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
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Tannous S, Darlot F, Cador M, Caille S. Flavor additives facilitate oral self-administration of nicotine solution in mice. Psychopharmacology (Berl) 2021; 238:2235-2247. [PMID: 33890131 DOI: 10.1007/s00213-021-05848-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 04/12/2021] [Indexed: 01/05/2023]
Abstract
RATIONALE Tobacco products are very addictive, partly because they contain nicotine which is reinforcing, but also because they include appealing aromas and tastes. Flavor additives are such sensory stimuli which enhance attractiveness, as well as use and abuse of tobacco and vaping products. Yet, the interaction between these flavor additives and nicotine remains poorly understood. OBJECTIVES We want to understand how flavors may reduce nicotine' aversive taste and how it may enhance its voluntary oral self-administration in mice. METHODS We first studied the effect of flavor additives on nicotine solution palatability in a free bottle choice paradigm. Second, we investigated the effect of vanilla flavoring on the different stages of nicotine (40 μg/ml) oral self-administration in mice. RESULTS We show that adding flavors increase nicotine palatability and facilitate acquisition and maintenance of oral self-administration when compared to nicotine-alone group. Mice adapt their operant behavior depending on changes in nicotine concentration. All mice reinstate nicotine seeking upon presentation of associated cues. Nevertheless, vanilla-flavored nicotine was not more reinforcing than vanilla-flavored water which was reinforcing enough to drive similar operant response rates. CONCLUSIONS Flavor additives increase nicotine oral consumption and help maintaining operant behavior in mice. Moreover, flavors can be very attractive and can have high reinforcing value by themselves. Thus, it is crucial that the investigation on how taste signals play an important role in modulating oral nicotine intake in rodent models remains explored.
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Affiliation(s)
- Salma Tannous
- Université de Bordeaux, CNRS, EPHE, INCIA, UMR5287, F-33000, Bordeaux, France
| | - Florence Darlot
- Université de Bordeaux, CNRS, EPHE, INCIA, UMR5287, F-33000, Bordeaux, France
| | - Martine Cador
- Université de Bordeaux, CNRS, EPHE, INCIA, UMR5287, F-33000, Bordeaux, France
| | - Stephanie Caille
- Université de Bordeaux, CNRS, EPHE, INCIA, UMR5287, F-33000, Bordeaux, France.
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6
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Jao NC, Levin ED, Simon MA, Hitsman B. Differences in Cognitive Task Performance, Reinforcement Enhancement, and Nicotine Dependence Between Menthol and Nonmenthol Cigarette Smokers. Nicotine Tob Res 2021; 23:1902-1910. [PMID: 34086950 DOI: 10.1093/ntr/ntab120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 06/02/2021] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Menthol has been shown to target similar brain regions and neural receptors as nicotine, yet the association between menthol cigarette use and cognitive performance remains unknown. AIMS AND METHODS This study examined differences in cognitive task performance between menthol (MS) and nonmenthol (NMS) cigarette smokers after acute cigarette consumption. Sixty white and black and/or African American, nonabstinent, MS (n = 30) and NMS (n = 30) were assessed presmoking and postsmoking their preferred cigarette on four computerized tasks: Continuous Performance Task (CPT; alerting attention), N-Back Task (working memory), Finger Tapping Task (motor control), and Apple Picker Task (reinforcement enhancement). Self-reported nicotine dependence and objective smoking topography measures were also compared between groups. RESULTS Initial unadjusted analyses showed a significant effect of cigarette type × time on CPT speed (p = .042), where MS improved while NMS group worsened in CPT speed after smoking. After controlling for baseline cigarette craving and cigarette nicotine levels, the effect of cigarette type × time for all cognitive outcomes was statistically nonsignificant (ps > .05). However, there remained a significant effect of cigarette type, where MS versus NMS had poorer CPT (p = .046) and N-Back Task accuracy (p = .006) but faster N-Back speed (p = .039). There were no statistically significant differences between groups on reinforcement enhancement, nicotine dependence, or smoking behavior outcomes (ps > .05). CONCLUSIONS Contrary to our hypotheses, results did not find a significant effect of cigarette type on the change in cognitive performance after acute smoking in nonabstinent smokers. Further studies are needed to clarify the specific pharmacological effects of nicotine and menthol on cognitive functioning. IMPLICATIONS The current study is the first to compare the potential enhancement of cognitive task performance after acute cigarette smoking between satiated menthol and nonmenthol cigarette smokers. Study results suggest that acute menthol cigarette use may not enhance cognitive function above and beyond nonmenthol cigarettes to increase dependence among menthol smokers. However, the contribution of other psychological factors (eg, craving, mood) and cigarette characteristics (eg, nicotine content) may be involved in cognitive function enhancement to perpetuate dependence and smoking persistence for menthol smokers.
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Affiliation(s)
- Nancy C Jao
- Department of Psychiatry and Human Behavior, Brown University Warren Alpert Medical School, and Center for Behavioral and Preventive Medicine, The Miriam Hospital, Providence, RI, USA
| | - Edward D Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Melissa A Simon
- Departments of Obstetrics and Gynecology, Preventive Medicine, and Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Brian Hitsman
- Departments of Preventive Medicine, Medical Social Sciences, and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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7
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Wickham RJ. The Biological Impact of Menthol on Tobacco Dependence. Nicotine Tob Res 2021; 22:1676-1684. [PMID: 31867627 DOI: 10.1093/ntr/ntz239] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022]
Abstract
In the 1920s, tobacco companies created a marketing campaign for what would one day be their most profitable series of products: mentholated tobacco cigarettes. Menthol provides the smoker with a pleasant mint flavor in addition to a cooling sensation of the mouth, throat, and lungs, giving relief from the painful irritation caused by tobacco smoke. Promising a healthier cigarette using pictures of doctors in white coats and even cartoon penguins, tobacco companies promoted these cigarettes to young, beginner smokers and those with respiratory health concerns. Today, smoking tobacco cigarettes causes one in five US Americans to die prematurely, crowning it as the leading cause of preventable death. In contrast to the dubious health claims by tobacco companies, mentholated cigarettes are in fact more addictive. Smokers of mentholated cigarettes have lower successful quit rates and in some cases are resistant to both behavioral and pharmacological treatment strategies. There is now considerable evidence, especially in the last 5 years, that suggest menthol might influence the addictive potential of nicotine-containing tobacco products via biological mechanisms. First, menthol alters the expression, stoichiometry, and function of nicotinic receptors. Second, menthol's chemosensory properties operate to mask aversive properties of using tobacco products. Third, menthol's chemosensory properties aid in serving as a conditioned cue that can both enhance nicotine intake and drive relapse. Fourth, menthol alters nicotine metabolism, increasing its bioavailability. This review discusses emerging evidence for these mechanisms, with an emphasis on preclinical findings that may shed light on why menthol smokers exhibit greater dependence. IMPLICATIONS Mentholated cigarettes have been shown to have greater addictive potential than their nonmentholated counterparts. Evidence is pointing toward multiple mechanisms of action by which menthol may alter tobacco dependence. Understanding menthol's biological functions as it pertains to nicotine dependence will be helpful in crafting novel pharmacotherapies that might better serve menthol smokers. In addition, a better understanding of menthol's pharmacology as it relates to tobacco dependence will be valuable for informing policy decisions on the regulation of mentholated cigarettes.
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Affiliation(s)
- Robert J Wickham
- Department of Psychology, Elizabethtown College, Elizabethtown, PA
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8
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Huynh YW, Raimondi A, Finkner A, Kuck JD, Selleck C, Bevins RA. Menthol blunts the interoceptive discriminative stimulus effects of nicotine in female but not male rats. Psychopharmacology (Berl) 2020; 237:2395-2404. [PMID: 32448943 PMCID: PMC7354904 DOI: 10.1007/s00213-020-05542-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/27/2020] [Indexed: 01/29/2023]
Abstract
RATIONALE Menthol is a widely used tobacco constituent that has shown to enhance nicotine's reinforcing effects. OBJECTIVE To determine whether injected menthol also alters nicotine's stimulus effects, we used a drug discrimination task. METHODS A total of 57 adult Sprague-Dawley rats (28M, 29F) received 20 positive and 20 negative days (intermixed) of discrimination training. On positive days, rats received a group-specific menthol and nicotine injection (VEH + 0.1 NIC, 1 M + 0.1 NIC, 5 M + 0.1 NIC, VEH + 0.4 NIC, 1 M + 0.4 NIC, 5 M + 0.4 NIC; mg/kg) before eight 15-s cue light presentations (conditioned stimulus (CS)), each followed by 4-s sucrose access. On negative days, all rats were injected with vehicle and saline before eight non-reinforced CS presentations. Next, rats underwent generalization testing with 30 dose combinations of menthol and nicotine. The change in drug-mediated anticipatory goal tracking during the CS was calculated as a difference score (CS minus pre-CS responding). RESULTS All groups readily acquired drug discrimination. However, difference scores for the 5M + 0.1 NIC group were lower for females. Additionally, females had lower scores for 0.05, 0.1, and 0.4 mg/kg nicotine generalization tests. The lowest nicotine dose discriminable from saline was 0.05 mg/kg for females but 0.025 mg/kg for males. Co-administration with 5 or 10 mg/kg menthol weakened discrimination performance between 0.1 and 0.4 mg/kg and between 0.1 and 0.05 mg/kg nicotine for 0.1 mg/kg nicotine training groups. CONCLUSIONS Female rats that were trained with 0.1 mg/kg nicotine were more sensitive to menthol's modulatory effects on nicotine's stimulus effects. This highlights the importance of taking sex and training dose into account when evaluating the interoceptive stimulus effects of nicotine and menthol.
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Affiliation(s)
- Y Wendy Huynh
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA
| | - Anthony Raimondi
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA
| | - Andrew Finkner
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA
| | - Jordan D Kuck
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA
| | - Carly Selleck
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA
| | - Rick A Bevins
- Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE, 68588-0308, USA.
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Sanchez V, Bakhti-Suroosh A, Chen A, Brunzell DH, Erisir A, Lynch WJ. Exercise during abstinence normalizes ultrastructural synaptic plasticity associated with nicotine-seeking following extended access self-administration. Eur J Neurosci 2019; 50:2707-2721. [PMID: 30888721 PMCID: PMC6742551 DOI: 10.1111/ejn.14408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/28/2019] [Accepted: 03/08/2019] [Indexed: 12/16/2022]
Abstract
Nicotine-craving progressively increases, or incubates, over abstinence following extended access self-administration. While not yet examined for nicotine, the incubation of cocaine-seeking is accompanied by changes in synaptic plasticity in the nucleus accumbens. Here, we determined whether such changes also accompany enhanced nicotine-seeking following extended access self-administration and abstinence, and whether exercise, a potential intervention for nicotine addiction, may exert its efficacy by normalizing these changes. Given that in humans, tobacco/nicotine use begins during adolescence, we used an adolescent-onset model. Nicotine-seeking was assessed in male rats following extended access nicotine or saline self-administration (23-hr/day, 10 days) and 10 days of abstinence, conditions known to induce the incubation of nicotine-seeking, using a within-session extinction/cue-induced reinstatement procedure. A subset of rats had 2-hr/day access to a running wheel during abstinence. Ultrastructural alterations of synapses in the nucleus accumbens core and shell were examined using electron microscopy. Nicotine-seeking was elevated following extended access self-administration and abstinence (in sedentary group), and levels of seeking were associated with an increase in the density of asymmetric (excitatory) and symmetric (inhibitory) synapses onto dendrites in the core, as well as longer asymmetric synapses onto spines, a marker of synaptic potentiation, in both the core and shell. Exercise normalized each of these changes; however, in the shell, exercise and nicotine similarly increased the synapse length. Together, these findings indicate an association between nicotine-seeking and synaptic plasticity in the nucleus accumbens, particularly the core, and indicate that the efficacy of exercise to reduce nicotine-seeking may be mediated by reversing these adaptations.
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Affiliation(s)
- Victoria Sanchez
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Anousheh Bakhti-Suroosh
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Andrew Chen
- Department of Psychology, University of Virginia, Charlottesville, Virginia
| | - Darlene H Brunzell
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville, Virginia
| | - Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
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10
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Abel JM, Nesil T, Bakhti-Suroosh A, Grant PA, Lynch WJ. Mechanisms underlying the efficacy of exercise as an intervention for cocaine relapse: a focus on mGlu5 in the dorsal medial prefrontal cortex. Psychopharmacology (Berl) 2019; 236:2155-2171. [PMID: 31161451 PMCID: PMC6626681 DOI: 10.1007/s00213-019-05208-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/25/2019] [Indexed: 01/08/2023]
Abstract
RATIONALE Exercise shows promise as a treatment option for addiction; but in order to prevent relapse, it may need to be introduced early in the course of treatment. OBJECTIVE We propose that exercise, by upregulating dorsal medial prefrontal cortex (dmPFC)-nucleus accumbens (NAc) transmission, offsets deficits in pathways targeting glutamate, BDNF, and dopamine during early abstinence, and in doing so, normalizes neuroadaptations that underlie relapse. METHODS We compared the effects of exercise (wheel running, 2-h/day) during early (days 1-7), late (days 8-14), and throughout abstinence (days 1-14) to sedentary conditions on cocaine-seeking and gene expression in the dmPFC and NAc core of male rats tested following 24-h/day extended-access cocaine (up to 96 infusions/day) or saline self-administration and protracted abstinence (15 days). Based on these data, we then used site-specific manipulation to determine whether dmPFC metabotropic glutamate receptor5 (mGlu5) underlies the efficacy of exercise. RESULTS Exercise initiated during early, but not late abstinence, reduced cocaine-seeking; this effect was strongly associated with dmPFC Grm5 expression (gene encoding mGlu5), and modestly associated with dmPFC Grin1 and Bdnf-IV expression. Activation of mGlu5 in the dmPFC during early abstinence mimicked the efficacy of early-initiated exercise; however, inhibition of these receptors prior to the exercise sessions did not block its efficacy indicating that there may be redundancy in the mechanisms through which exercise reduces cocaine-seeking. CONCLUSION These findings indicate that addiction treatments, including exercise, should be tailored for early versus late phases of abstinence since their effectiveness will vary over abstinence due to the dynamic nature of the underlying neuroadaptations.
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Affiliation(s)
- Jean M. Abel
- Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA
| | - Tanseli Nesil
- Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA
| | | | - Patrick A. Grant
- Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA
| | - Wendy J. Lynch
- Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA,Corresponding Author: Wendy J. Lynch, PhD, Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, PO Box 801402, Charlottesville, VA 22904; Tel: (434) 243-0580; Fax: (434) 973-7031;
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