Figure 1.

Active immunization with GNC-KLH prevents cocaine (0.25 mg/infusion) self-administration relapse in rats. Mean response rates per 1-h session are shown during baseline training, extinction (saline substitution), relapse (noncontingent cocaine delivery), and free access to cocaine, under a fixed ratio 1:20 schedule of reinforcement. Animals were treated with either the cocaine conjugate GNC-KLH (A) or the carrier protein KLH (B). * indicate a significant difference between groups during the relapse phase, P < 0.029, ANOVA. † indicate that response rate values for each group were significantly different from their respective baseline values, P < 0.01, ANOVA.