Acquisition and Maintenace of Intravenous Cocaine Self-Administration in Lewis and Fischer Inbred Rat Strains
Tested whether Lewis and Fischer rat strains differ in acquisition or maintenance of intravenous cocaine self-administration. Acquisition of cocaine self-administration was examined in separate groups that were allowed 15 days to acquire the operant at one of three cocaine doses (0.25, 0.5, or 1.0 mg/kg/infusion). Compared to Fischer rats, Lewis rats acquired cocaine self-administration after fewer training trials and at lower doses. After maintenance, both strains showed characteristic extinction responding with saline substitution and dose-related responding to cocaine, although Fischer rats tended to show higher response rates. Finally, cocaine plasma levels, obtained after an intravenous cocaine infusion (1.0 mg/kg), showed no strain differences suggesting that the strain difference in acquisition was not due to cocaine pharmacokinetics.
Kosten, Therese A., Miserendino, Mindy, et al. "Acquisition and Maintenace of Intravenous Cocaine Self-Administration in Lewis and Fischer Inbred Rat Strains." Brain Research 778.2 (1997): 418-429.