Abstract Rationale: 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. Method: 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.
Bibliographical noteFunding Information:
The authors thank Drs. Andy Harris and Natalie Zlebnik for their comments on this manuscript, Clare Chamberlain, Adam Greer, Seth Johnson, Sarah Korthauer, Jared Mitchell, Amy Sakao, and Heather Veglahn for the technical assistance, and Dr. Krista Walkowiak, DVM, for veterinary care. Funding was provided by the National Institute on Drug Abuse (NIDA) grant P50 DA033942 (MEC) and a NIDA training grant T32 DA007097 (JRS—Dr. Tom Molitor-PI).
© 2015 Springer-Verlag Berlin Heidelberg.
- Acute cocaine
- Delay discounting