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Zandonai T, Tam E, Bruseghini P, Pizzolato F, Franceschi L, Baraldo M, Capelli C, Cesari P, Chiamulera C. The effects of oral smokeless tobacco administration on endurance performance. JOURNAL OF SPORT AND HEALTH SCIENCE 2018; 7:465-472. [PMID: 30450256 PMCID: PMC6226421 DOI: 10.1016/j.jshs.2016.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 09/14/2016] [Accepted: 11/08/2016] [Indexed: 06/09/2023]
Abstract
BACKGROUND Smokeless tobacco is widely used by athletes to enhance performance. Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems, involving tissue blood flow and circulatory vasoreactivity. The aim of this study was to investigate the effects of the oral smokeless tobacco (Swedish snus (SS)) on the perception of fatigue and time to exhaustion (TTE) during moderate-intensity aerobic exercise. METHODS Fourteen healthy non-tobacco male users were recruited for a double-blind, controlled crossover design (SS vs. snus placebo (SP)). Subjects were tested for 3 sessions: experimental session 1 (Exp1) consisted of an incremental test to determine the maximal aerobic power output (Wmax), whereas Exp2 and Exp3 consisted of exercising at 65%Wmax until exhaustion in SS or SP conditions. During Exp2 and Exp3, muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy, and the rating of perceived exertion (RPE) was recorded. RESULTS Comparing SS with SP tests, significant differences (p < 0.05) were found in the values of cerebral (~3%) and muscular tissues oxygenation (~4%) in the first 30 min of exercise. The RPE values were not significantly different between the 2 conditions (SS vs. SP). No significant difference was found in TTE (SS: 54.25 ± 21.84 min; SP: 50.01 ± 17.03 min). CONCLUSION This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion, but this did not affect fatigue perception and TTE. The results showed that snus could not be considered an ergogenic substance in non-tobacco users.
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Affiliation(s)
- Thomas Zandonai
- Neuropsychopharmacology Laboratory, Department of Diagnostic and Public Health, University of Verona, Verona 37134, Italy
- Mind, Brain and Behavior Research Center CIMCYC, Department of Experimental Psychology, University of Granada, Granada 18071, Spain
| | - Enrico Tam
- Department of Neurosciences, Biomedicine and Movement Sciences, School of Exercise and Sport Science, University of Verona, Verona 37131, Italy
| | - Paolo Bruseghini
- Department of Neurosciences, Biomedicine and Movement Sciences, School of Exercise and Sport Science, University of Verona, Verona 37131, Italy
| | - Fabio Pizzolato
- Department of Neurosciences, Biomedicine and Movement Sciences, School of Exercise and Sport Science, University of Verona, Verona 37131, Italy
| | - Loretta Franceschi
- Department of Experimental and Clinical Medical Sciences, University of Udine, Udine 33100, Italy
| | - Massimo Baraldo
- Department of Experimental and Clinical Medical Sciences, University of Udine, Udine 33100, Italy
| | - Carlo Capelli
- Department of Neurosciences, Biomedicine and Movement Sciences, School of Exercise and Sport Science, University of Verona, Verona 37131, Italy
- Department of Physical Performances, Norwegian School of Sport Sciences, Oslo N-0806, Norway
| | - Paola Cesari
- Department of Neurosciences, Biomedicine and Movement Sciences, School of Exercise and Sport Science, University of Verona, Verona 37131, Italy
| | - Cristiano Chiamulera
- Neuropsychopharmacology Laboratory, Department of Diagnostic and Public Health, University of Verona, Verona 37134, Italy
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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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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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Neuroadaptation in nicotine addiction: update on the sensitization-homeostasis model. Brain Sci 2012; 2:523-52. [PMID: 24961259 PMCID: PMC4061804 DOI: 10.3390/brainsci2040523] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/05/2012] [Accepted: 09/25/2012] [Indexed: 01/24/2023] Open
Abstract
The role of neuronal plasticity in supporting the addictive state has generated much research and some conceptual theories. One such theory, the sensitization-homeostasis (SH) model, postulates that nicotine suppresses craving circuits, and this triggers the development of homeostatic adaptations that autonomously support craving. Based on clinical studies, the SH model predicts the existence of three distinct forms of neuroplasticity that are responsible for withdrawal, tolerance and the resolution of withdrawal. Over the past decade, many controversial aspects of the SH model have become well established by the literature, while some details have been disproven. Here we update the model based on new studies showing that nicotine dependence develops through a set sequence of symptoms in all smokers, and that the latency to withdrawal, the time it takes for withdrawal symptoms to appear during abstinence, is initially very long but shortens by several orders of magnitude over time. We conclude by outlining directions for future research based on the updated model, and commenting on how new experimental studies can gain from the framework put forth in the SH model.
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Corrigall WA. Hypocretin mechanisms in nicotine addiction: evidence and speculation. Psychopharmacology (Berl) 2009; 206:23-37. [PMID: 19529922 DOI: 10.1007/s00213-009-1588-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 06/01/2009] [Indexed: 01/11/2023]
Abstract
BACKGROUND The hypocretin/orexin system has been implicated in arousal mechanisms, sleep, and sleep disorders, including narcolepsy, and more recently in drug addiction. Theoretically, hypocretin (hcrt) mechanisms appear to be potential substrates for nicotine addiction: arousal and attentional mechanisms influence use and withdrawal symptoms, and hcrt systems overlap anatomically with a number of brain regions associated with nicotine addiction. OBJECTIVE This review summarizes the studies that have examined hcrt mechanisms in the effects of nicotine and describes hcrt innervation of, and effects in, several brain regions implicated in nicotine addiction. The review speculates on the possible mechanisms by which hcrt may contribute to nicotine addiction in these regions, with the objective of encouraging research in this area. RESULTS In a small literature, both experimenter-administered and self-administered nicotine have been shown to elicit or depend on hcrt signaling. However, although untested in experimental designs, there is compelling evidence that hcrt mechanisms in the ventral tegmental area, the pontine region, thalamocortical circuits, the prefrontal cortex, and the amygdala could have a broad influence on nicotine addiction. CONCLUSIONS Evidence reviewed leads to the conclusion that hcrt mechanisms could mediate several dimensions of nicotine addiction, including a multi-faceted regulation of mesocorticolimbic dopaminergic function, but beyond dopaminergic mechanisms, hcrt could influence nicotine use and relapse during abstinence through broadly based arousal/attentional effects. These speculative ideas need to be examined experimentally; the potential gains are a more thorough understanding of the pathophysiology of nicotine addiction, and the discovery of novel targets for the development of pharmacotherapeutics.
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Suarez SV, Amadon A, Giacomini E, Wiklund A, Changeux JP, Le Bihan D, Granon S. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study. Psychopharmacology (Berl) 2009; 202:599-610. [PMID: 18818904 DOI: 10.1007/s00213-008-1338-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 09/10/2008] [Indexed: 01/08/2023]
Abstract
RATIONALE The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity beta2-containing nicotinic receptors (beta2*nAChRs) are located. OBJECTIVES We intend to see which brain circuits are activated when nicotine is given in animals naïve for nicotine and whether the beta2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. MATERIALS AND METHODS We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and beta2 knockout (KO) mice. RESULTS Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, beta2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via alpha7 nicotinic receptors. CONCLUSIONS Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on beta2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice.
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Affiliation(s)
- S V Suarez
- Unité de Neurobiologie Intégrative du Système Cholinergique, URA CNRS 2182, Institut Pasteur, Département de Neuroscience, 25 rue du Dr. Roux, 75015 Paris, France
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Gozzi A, Schwarz A, Reese T, Bertani S, Crestan V, Bifone A. Region-specific effects of nicotine on brain activity: a pharmacological MRI study in the drug-naïve rat. Neuropsychopharmacology 2006; 31:1690-703. [PMID: 16292320 DOI: 10.1038/sj.npp.1300955] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have applied pharmacological magnetic resonance imaging (phMRI) methods to map the functional response to nicotine in drug-naïve rats. Nicotine (0.35 mg/kg intravenous (i.v.)) increased relative cerebral blood volume (rCBV) in cortical (including medial prefrontal, cingulate orbitofrontal, insular) and subcortical (including amygdala and dorsomedial hippocampus) structures. The pharmacological specificity of the effect was demonstrated by acute pretreatment with the nicotinic acetylcholine receptor (nAChR) ion-channel-blocking agent mecamylamine, which suppressed the rCBV response to nicotine. Control experiments with norepinephrine, a potent non-brain-penetrant vasopressor, at a dose that mimics the cardiovascular response induced by nicotine were performed to assess the potential confounding effects of peripheral blood pressure changes induced by nicotine. In an attempt to highlight the relative contribution of different nAChR subtypes to the observed activation pattern of nicotine, we also investigated the central phMRI response to an acute challenge with (R)-N-(1-azabicyclo[2.2.2]oct-3-yl)(5-(2-pyridyl)thiophene-2-carboxamide) (cpdA, at 5, 10, 20, and 30 mg/kg i.v.) and 5-iodo-A-85380 (5IA, 5 mg/kg i.v.). CpdA is a selective agonist at homomeric alpha7 nAChRs, while 5IA features high in vivo affinity for the alpha4beta2* and other less-abundant beta2-containing nicotinic receptors. CpdA did not produce significant rCBV changes at any of the doses tested, whereas 5IA induced a pattern of activation very similar to that induced by nicotine. The lack of phMRI response to cpdA together with the high spatial overlap between the activation profile of nicotine and 5IA, suggest that the acute functional response to nicotine in drug-naïve rats is mediated by beta2-containing nAChR isoforms, presumably belonging to the alpha4beta2* subtype.
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Affiliation(s)
- Alessandro Gozzi
- Department of Neuroimaging, Centre of Excellence for Drug Discovery, Psychiatry, GlaxoSmithKline Medicines Research Centre, Verona, Italy.
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Choi JK, Mandeville JB, Chen YI, Kim YR, Jenkins BG. High resolution spatial mapping of nicotine action using pharmacologic magnetic resonance imaging. Synapse 2006; 60:152-7. [PMID: 16715493 DOI: 10.1002/syn.20284] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nicotine is one of the most addictive substances known. To better understand the mechanisms of action, we mapped the regional brain response to nicotine administration using pharmacologic magnetic resonance imaging (phMRI) in rats. We measured the regional response of relative cerebral blood volume (rCBV) in rats to a challenge of 0.07 mg/kg (0.43 micromol/kg) of nicotine. The areas of the brain with significant and reproducible changes in the rCBV response were (in descending order of magnitude) infralimbic cortex, hippocampus (subiculum), agranular insular/pyriform cortex, visual cortex, interpeduncular area, nucleus accumbens, cingulate cortex, thalamus, and septum. This pattern of response is consistent with stimulation of both cholinergic and dopaminergic neuronal pathways and is consistent with the known behavioral properties of nicotine. The peak CBV response to nicotine occurred between 9 and 13 min depending upon brain region, and the average full width half-maximum of the rCBV response was 27 min. The high spatial and temporal resolution of the phMRI technique lends itself well to further, more detailed, studies of nicotine dynamics.
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Affiliation(s)
- Ji-Kyung Choi
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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