title: Impact of strain and D-amphetamine on impulsivity (delay discounting) in inbred mice.
abstract: BACKGROUND
  Many studies have shown that human drug abusers are more impulsive than nonusers, but the mechanisms underlying this difference are unknown. C57BL/6J (B6) and DBA/2J (D2) mouse strains differ in sensitivity to the associative effects and in self-administration of several drugs of abuse.
  
  
  OBJECTIVE
  To determine whether these strains exhibit differences in impulsivity that might correspond to the differences in phenotypes related to drug seeking.
  
  
  METHODS
  We examined impulsive choice in drug-naive B6 and D2 mice using a delay discounting protocol (adjusting amount procedure, J Exp Anal Behav 67:353-366, 1997).
  
  
  RESULTS
  Contrary to our initial expectations, we observed greater delay discounting (higher impulsivity) in D2 rather than in B6 mice. For both strains, discounting was enhanced by 0.80 and 1.20 mg/kg (i.p.) D-amphetamine relative to saline.
  
  
  CONCLUSIONS
  Data demonstrate the sensitivity of the procedure to strain differences and pharmacological manipulations. However, additional data are required to clarify the factors underlying this difference and how the delay discounting measure of impulsivity relates to phenotypic models of drug reinforcement and drug seeking.
authors.affiliation: Department of Behavioral Neuroscience L-470, Oregon Health and Science University, Portland, OR 97239, USA. helmsc@ohsu.edu
authors.forename: Christa M
authors.initials: CM
authors.lastname: Helms
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Reeves
authors.forename: Suzanne H
authors.initials: SH
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects*; D003913:Dextroamphetamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D007175:Impulsive Behavior / Q000523:psychology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D012054:Reinforcement, Psychology; D013045:Species Specificity
chemical_list: D018491:Dopamine Agonists; D003913:Dextroamphetamine