Discrepant effects of acute cocaine on impulsive choice (delay discounting) in female rats during an increasing- and adjusting-delay procedure.
BACKGROUND
The relationship between impulsive choice and cocaine use in humans has been well established, although the causal role between these variables is complex. To disentangle this relationship, studies using rats have focused on how acute or chronic cocaine alters impulsive choice. A predominance of studies has focused on chronic cocaine regimens, but few have assessed acute cocaine's effects on impulsive choice.


OBJECTIVE
The current study assessed if acute cocaine administrations alter delay discounting of rats in two common impulsive choice procedures.


METHODS
Baseline delay discounting rates were determined in female rats using both an increasing- and adjusting-delay procedure. Once stable, a range of acute cocaine injections (2, 5, and 15 mg/kg i.p.) was administered prior to both procedures.


RESULTS
Baseline delay discounting rates were positively correlated between the increasing- and adjusting-delay procedures. Acute administrations of cocaine produced a dose-dependent decrease in preference for the large alternative in the increasing-delay procedure but had no effect in the adjusting-delay procedure.


CONCLUSIONS
The concordance of delay discounting rates across the two choice procedures suggests that both quantify the same underlying components of impulsive choice. However, manipulations that disrupt large alternative preference may not be readily detected under the adjusting-delay procedure unless control conditions are employed.
Department of Psychiatry, University of Minnesota, MMC 392, Minneapolis, MN, 55455, USA, jsmethells@gmail.com.
John R
JR
Smethells
Marilyn E
ME
Carroll
D000818:Animals; D002755:Choice Behavior / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000523:psychology; D065786:Delay Discounting / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007175:Impulsive Behavior / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D051381:Rats; D017208:Rats, Wistar
D003042:Cocaine