Original Investigation

Psychopharmacology

, Volume 188, Issue 2, pp 144-151

Impact of strain and d-amphetamine on impulsivity (delay discounting) in inbred mice

  • Christa M. HelmsAffiliated withDepartment of Behavioral Neuroscience L-470, Oregon Health and Science University Email author 
  • , Jamie M. ReevesAffiliated withDepartment of Behavioral Neuroscience L-470, Oregon Health and Science University
  • , Suzanne H. MitchellAffiliated withDepartment of Behavioral Neuroscience L-470, Oregon Health and Science UniversityDepartment of Psychiatry, Oregon Health & Science University

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Abstract

Rationale

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.

Keywords

Impulsivity Choice Delay discounting Amphetamine Inbred strains DBA/2J C57BL/6J