title: Effects of stressors on the reinforcing efficacy of nicotine in adolescent and adult rats.
abstract: OBJECTIVE
  Stress increases drug intake. This depends on the stressor, drug, and aspect of drug seeking assessed. The objectives of these experiments done in adolescent and adult male rats were to (1) examine social defeat effects on acquisition of nicotine self-administration (SA) and the reinforcing efficacy of nicotine and (2) determine the effects of acute exposure to intermittent footshock (FS) or yohimbine on the reinforcing efficacy of nicotine.
  
  
  METHODS
  In experiment 1, rats received four defeat exposures prior to nicotine SA acquisition and progressive ratio (PR) SA sessions (30 μg/kg nicotine/infusion). Exposure to an olfactory cue previously paired with defeat was also tested on responding maintained by nicotine on the PR schedule. In experiments 2 and 3, the effects of FS (5 and 10 min) or yohimbine (0.625 and 1.25 mg/kg, i.p.) on PR responding for nicotine (15, 30, or 60 μg/kg/infusion) were assessed. Adolescents were aged PD34-36 and adults PD81-85 at the beginning of nicotine SA training.
  
  
  RESULTS
  Defeat did not affect nicotine SA acquisition. Prior exposure to defeat or a defeat-paired olfactory cue did not affect PR responding for nicotine. FS modestly decreased PR responding in adolescents at the middle nicotine infusion dose. Yohimbine increased PR responding independent of nicotine infusion dose and age.
  
  
  CONCLUSIONS
  Together with previous work with other drugs, our data indicate that the effects of stress on the reinforcing efficacy of nicotine are stressor- and drug-dependent. This suggests that there is heterogeneity among stressors on how they affect neuronal systems underlying drug intake.
authors: Neurobiology of Alcohol Laboratory, Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada.
authors: Sheng
authors: S
authors: Zou
authors: Douglas
authors: D
authors: Funk
authors: Megan J
authors: MJ
authors: Shram
authors: A D
authors: AD
authors: Lê
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D003463:Cues; D004291:Dominance-Subordination; D004305:Dose-Response Relationship, Drug; D058999:Drug-Seeking Behavior / Q000187:drug effects / Q000502:physiology*; D004597:Electroshock; D008297:Male; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D009812:Odorants; D020318:Rats, Long-Evans; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012646:Self Administration; D013315:Stress, Psychological / Q000503:physiopathology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D018722:Nicotinic Agonists; D015016:Yohimbine; D009538:Nicotine