Cocaine Dose and Self-Administration History, but Not Initial Cocaine Locomotor Responsiveness, Affects Sensitization to the Motivational Effects of Cocaine in Rats

• DOI: 10.1124/jpet.112.194092
• Publication Date: 2012-04-21T00:45:56Z
• Authors: Bruce H. Mandt; Emily Gomez; Nickie L. Johnston; Nancy R. Zahniser; Richard M. Allen
• Keywords: Self-administration; Behavioral sensitization

Cocaine addiction is a significant and complex disease. Part of this complexity caused by the variability drug experience early in use (initial responsiveness, amount use, etc.). In rats, individual differences initial cocaine responsiveness self-administration history both predict development sensitization, putative mechanism contributing to addiction. Here, we sought determine role these factors dose on sensitization cocaine9s motivational effects during earliest stages self-administration. Rats were classified as either low or high responders (LCRs HCRs, respectively) based acute cocaine-induced locomotor activity (10 mg/kg i.p.) before learning self-administer (0.6 mg/kg/infusion i.v.) under fixed ratio 1 (FR1) schedule reinforcement. After acquisition, rats self-administered 1.2 mg/kg/infusion) progressive (PR) reinforcement immediately after an additional five FR1 sessions mg/kg/infusion). No LCR/HCR observed. However, regardless classification, exposure higher produced PR (i.e., increased break points) escalation consumption FR schedule. Thus, our results reveal novel model for studying very acquisition suggest that may be important process.