Cocaine-Induced Locomotor Sensitization Persists In Rats That Escalate Cocaine Self-Administration In A Short-Access Procedure

The role of sensitization in cocaine addiction remains debatable. In rats, non-contingent cocaine-induced locomotor sensitization is well documented. However, the relationship between this measure and measures of cocaine self-administration is less clear. For example, repeated non-contingent cocaine pre-exposure enhances acquisition of self-administration and increases break points (BPs) for cocaine. Following escalation of intake or BPs, however, some studies report tolerance to cocaine’s locomotor-stimulating effects. Importantly, sensitization is often assessed after long self-administration histories or high levels of cocaine exposure. We have recently developed a method for assessing escalation early in self-administration. Using this method, here we report on the relationship between cocaine-induced locomotor sensitization and escalation early in the drug-taking process. Cocaine-induced (10 mg/kg, i.p.) locomotor activity was assessed on 3 occasions: 1) in a drug-naive state, 2) after 5 days of non-...