Nicotine Addiction: PSYCOLOQUY Call for Commentary

NICOTINE-ADDICTION SYMPOSIUM The target articles below have been published, as part of an ongoing workshop on nicotine addiction, in Psycoloquy, a refereed journal of Open Peer Commentary sponsored by the American Psychological Association (APA) and indexed in Current Contents and in PsycInfo (http://www.apa.org/psycinfo/about/covlist.html). Qualified professional biobehavioral, neural or cognitive scientists are hereby invited to submit Open Peer Commentary on one or more of these target articles. If you are not familiar with the format or acceptance criteria for Psycoloquy commentaries (all submissions are refereed), please consult the websites below or email for instructions: SUBMIT COMMENTARIES TO: psyc(a)pucc.princeton.edu URLs: http://www.princeton.edu/~harnad/psyc.html http://www.cogsci.soton.ac.uk/psyc TARGET ARTICLES on which commentary is invited: (1) Balfour, D. (2001), The Role of Mesolimbic Dopamine in Nicotine Dependence. Psycoloquy 12(001) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.001 ABSTRACT: It is now widely accepted that a majority of habitual tobacco smokers become addicted to the nicotine present in the smoke. This brief review focuses on the evidence that nicotine exerts on the mesolimbic dopamine (DA) system that are entirely consistent with it having the properties of a psychostimulant drug of abuse. Thus, the ability of nicotine to reinforce self- administration in experimental animals depends upon its ability to stimulate the DA-secreting neurones which project to the nucleus accumbens. Microdialysis studies show that acute nicotine preferentially stimulates DA overflow in the shell of the nucleus accumbens, whereas subchronic nicotine causes sensitisation of its stimulatory effects on DA overflow in the core of the structure. The presentation discusses the evidence that stimulation of DA overflow in the accumbens shell is required to elicit or, more likely, signal the 'rewarding' properties of the drug which reinforce self-administration. Based on the results of studies with other psychostimulant drugs, it is possible that these effects are mediated by the D-3 receptors that are found in relatively high density in the subdivision of the structure. The sensitised effects of subchronic nicotine in the core of the accumbens are thought to mediate the transfer from 'drug-liking' to 'drug-seeking' behaviour and, therefore, to be of fundamental importance to the development of dependence. The nature of the receptor(s) involved remains to be established although there is circumstantial evidence for a role of both D-1 and D-2 receptors. Studies reported in more recent years have suggested that increased DA overflow in the accumbens is not, in itself, sufficient to account for the rewarding properties of addictive drugs. The review concludes by discussing the evidence that drugs of dependence preferentially increase DA overflow into an extra-synaptic compartment where it gains access, by a process of volume transmission, to extra-synaptic DA receptors located on adjacent cells. These receptors, it is proposed, facilitate the way in which we learn about cues associated with pleasurable stimuli and the ways in which the may be experienced again. (2) Le Houezec, J. (2001), Non-Dopaminergic Pathways in Nicotine Dependence. Psycoloquy 12 (002) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.002 ABSTRACT: There is strong evidence that nicotine exerts its positive reinforcing effects through the dopaminergic reward system. However, recent literature has shown that nicotine can modulate other neurotransmitter systems, mainly through pre-synaptic cholinergic receptors. This paper focuses on some of the systems that could participate in the nicotine dependence process. (3) Oscarson, M. (2001), Nicotine Metabolism by the Polymorphic Cytochrome P450 2A6 (CYP2A6) Enzyme: Implications for Interindividual Differences in Smoking Behaviour. Psycoloquy 12 (003) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.003 ABSTRACT: Cytochrome P450 2A6 (CYP2A6) is one of the most important enzymes in human nicotine metabolism. Genetic polymorphisms in the CYP2A6 gene causes important interindividual variability in CYP2A6 activity and this variation can explain some of the interindividual variability in nicotine metabolism previously reported. Here I summarise the current knowledge about the CYP2A6 polymorphism, and also discuss the potential importance of this polymorphism for differences in smoking behaviour. (4) Sivilotti, L. (2001), Nicotinic Receptors: Molecular Issues. Psycoloquy 12 (004) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.004 ABSTRACT: Expression of neuronal nicotinic receptors in Xenopus oocytes has shown that several different subunit combinations are functional, with a range of pharmacological and biophysical properties. In the nervous system, nicotinic receptors are found on the soma or the presynaptic terminals of neurones: the precise molecular identification of these receptor subtypes remains a challenge to pharmacology. (5) Smith, G. & Sachse, C. (2001), A Role for CYP2D6 in Nicotine Metabolism? Psycoloquy 12 (005) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.005 ABSTRACT: Nicotine is known to be metabolised to its major metabolite cotinine by members of the cytochrome P450 monooxygenase superfamily. Although CYP2A6 has now been identified as the principal enzyme which catalyses this biotransformation, CYP2D6 is also an active nicotine C-oxidase. Some 8% of the Caucasian population have reduced or absent CYP2A6 activity; CYP2D6 may play a significant role in nicotine metabolism in these individuals. CYP2D6 is highly polymorphic - a number of studies linking CYP2D6 genotype to smoking behaviour have now been published. CYP2D6 may have an important constitutive function in neurotransmitter metabolism and CYP2D6 genotype is thought to be a critical determinant in the success of antidepressant drug treatment. (6) Wonnacott, S. (2001), Nicotinic Receptors in Relation to Nicotine Addiction. Psycoloquy 12 (006) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.006 ABSTRACT: The first step in processing nicotine's effects on the brain is the drug's interaction with neuronal nicotinic receptors (nAChR). The diversity of nAChR subtypes, their various modes of response (activation, desensitisation, prolonged inactivation), and the complex pharmacokinetics of nicotine delivery conspire to make this a complex issue that is difficult to unravel. The alpha4beta2 nAChR subtype has the highest affinity for nicotine and is the primary candidate for mediating nicotine's central effects. Chronic nicotine exposure (in both humans, animals and cell culture systems) leads to an increase in numbers of alpha4beta2 nAChR (upregulation), with functional implications for withdrawal. However, there is little evidence presently that nAChR upregulation is pertinent to the induction or maintenance of dependence. However, the particular characteristics of the alpha7 subtype of nAChR suggest that it may participate in long term changes in synaptic efficacy that could be relevant to nicotine dependence. ------------------------------------------------------------------------- Below is a list of other recently published PSYCOLOQUY target articles that are also currently undergoing Open Peer Commentary. Commentary is invited on these articles too: INDIVIDUAL TARGET ARTICLES: Navon, D. (2001), The Puzzle of Mirror Reversal: A View From Clockland. Psycoloquy 12 (017) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.017 Kramer, D. & Moore, M. (2001), Gender Roles, Romantic Fiction and Family Therapy. Psycoloquy 12 (024) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.024 Sherman, J. A. (2001), Evolutionary Origin of Bipolar Disorder (EOBD). Psycoloquy 12 (028) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.028 Overgaard, M. (2001), The Role of Phenomenological Reports in Experiments on Consciousness. Psycoloquy 12 (029) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.029 Crow, T. J. (2000) Did Homo Sapiens Speciate on the Y Chromosome? Psycoloquy 11 (001) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.001 Margolis, H. (2000) Wason's Selection Task with A Reduced Array Psycoloquy 11 (005) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.005 Place, U. T. (2000) The Role of the Hand in the Evolution of Language Psycoloquy 11 (007) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.007 Green, C. D. (2000) Is AI the Right Method for Cognitive Science? Psycoloquy 11 (061) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.061 Reifman, A. (2000) Revisiting the Bell Curve Psycoloquy 11 (099) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.099 MULTIPLE BOOK REVIEWS: Ben-Ze'ev, A. (2001), The Subtlety of Emotions. Psycoloquy 12 (007) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.007 Miller, G. F. (2001), The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature. Psycoloquy 12 (008) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.008 Zachar, P. (2001), Psychological Concepts and Biological Psychiatry: A Philosophical Analysis. Psycoloquy 12 (023) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.023 Bolton, D. & Hill, J. (2001), Mind, Meaning & Mental Disorder: The Nature of Causal Explanation in Psychology & Psychiatry. Psycoloquy 12 (018) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.018 Praetorius, N. (2001), Principles of Cognition, Language and Action: Essays on the Foundations of a Science of Psychology. Psycoloquy 12 (027) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?12.027 Carstairs-McCarthy, A. (2000) The Origins of Complex Language Psycoloquy 11 (082) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.082 Storfer, M. D. (2000) Myopia, Intelligence, and the Expanding Human Neocortex Psycoloquy 11 (083) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.083 Tenopir, C. & King, D. W. (2000) Towards Electronic Journals: Realities for Scientists, Librarians, and Publishers Psycoloquy 11 (084) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.084 Sheets-Johnston, M. (2000) The Primacy of Movement Psycoloquy 11 (098) http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.098 SUBMIT COMMENTARIES TO: psyc(a)pucc.princeton.edu URLs: http://www.princeton.edu/~harnad/psyc.html http://www.cogsci.soton.ac.uk/psyc