title: Role of Central Amygdala Neuronal Ensembles in Incubation of Nicotine Craving.
abstract: The craving response to smoking-associated cues in humans or to intravenous nicotine-associated cues in adult rats progressively increases or incubates after withdrawal. Here, we further characterized incubation of nicotine craving in the rat model by determining whether this incubation is observed after adolescent-onset nicotine self-administration. We also used the neuronal activity marker Fos and the Daun02 chemogenetic inactivation procedure to identify cue-activated neuronal ensembles that mediate incubation of nicotine craving. We trained adolescent and adult male rats to self-administer nicotine (2 h/d for 12 d) and assessed cue-induced nicotine seeking in extinction tests (1 h) after 1, 7, 14, or 28 withdrawal days. In both adult and adolescent rats, nicotine seeking in the relapse tests followed an inverted U-shaped curve, with maximal responding on withdrawal day 14. Independent of the withdrawal day, nicotine seeking in the relapse tests was higher in adult than in adolescent rats. Analysis of Fos expression in different brain areas of adolescent and adult rats on withdrawal days 1 and 14 showed time-dependent increases in the number of Fos-positive neurons in central and basolateral amygdala, orbitofrontal cortex, ventral and dorsal medial prefrontal cortex, and nucleus accumbens core and shell. In adult Fos-lacZ transgenic rats, selective inactivation of nicotine-cue-activated Fos neurons in central amygdala, but not orbitofrontal cortex, decreased "incubated" nicotine seeking on withdrawal day 14. Our results demonstrate that incubation of nicotine craving occurs after adolescent-onset nicotine self-administration and that neuronal ensembles in central amygdala play a critical role in this incubation.
  
  
  
  The craving response to smoking-associated cues in humans or to intravenous nicotine-associated cues in adult rats progressively increases or incubates after withdrawal. It is currently unknown whether incubation of craving also occurs after adolescent-onset nicotine self-administration. The brain areas that mediate such incubation are also unknown. Here, we used a rat model of incubation of drug craving, the neuronal activity marker Fos, and the Daun02 chemogenetic inactivation method to demonstrate that incubation of nicotine craving is also observed after adolescent-onset nicotine self-administration and that neuronal ensembles in the central nucleus of the amygdala play a critical role in this incubation in adult rats.
authors.affiliation: Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada M5S 2S1, Douglas.Funk@camh.ca.
authors.forename: Douglas
authors.identifier: 0000-0003-2436-5795
authors.initials: D
authors.lastname: Funk
authors.affiliation: Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada M5S 2S1.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Coen
authors.affiliation: Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada M5S 2S1.
authors.forename: Sahar
authors.identifier: 0000-0003-3157-6013
authors.initials: S
authors.lastname: Tamadon
authors.affiliation: Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse-National Institutes of Health, Baltimore, Maryland 21224.
authors.forename: Bruce T
authors.identifier: 0000-0001-5804-7061
authors.initials: BT
authors.lastname: Hope
authors.affiliation: Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse-National Institutes of Health, Baltimore, Maryland 21224.
authors.forename: Yavin
authors.identifier: 0000-0002-8242-3319
authors.initials: Y
authors.lastname: Shaham
authors.affiliation: Neurobiology of Alcohol Laboratory, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada M5S 2S1, Departments of Pharmacology and Toxicology and Department of Psychiatry, University of Toronto, Toronto, Canada M5S 1A8, and.
authors.forename: A D
authors.initials: AD
authors.lastname: Lê
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D066274:Central Amygdaloid Nucleus / Q000166:cytology* / Q000378:metabolism; D066249:Craving / Q000502:physiology*; D003630:Daunorubicin / Q000031:analogs & derivatives / Q000378:metabolism; D005108:Extinction, Psychological; D005260:Female; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000008:administration & dosage*; D016761:Oncogene Proteins v-fos / Q000235:genetics / Q000378:metabolism; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D055647:Rats, Transgenic; D012646:Self Administration; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology; D013395:Sucrose / Q000008:administration & dosage; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: C576267:N-(4''-(galactopyranosyl)-3''-nitrobenzyloxycarbonyl)daunomycin; D018722:Nicotinic Agonists; D016761:Oncogene Proteins v-fos; D013395:Sucrose; D009538:Nicotine; D001616:beta-Galactosidase; D010751:Phosphopyruvate Hydratase; D003630:Daunorubicin
keywords: Daun02; Fos; central amygdala; incubation of craving; nicotine; orbitofrontal cortex