Figure 3.

Reversing the attenuating effects of CP 94,253 on methamphetamine (0.1 mg/kg, i.v.) self-administration with SB 224,289 during tests that occurred preabstinence. On the first test day, rats (group 1: n=14, group 2: n=17) received a pretreatment of either vehicle (Veh, white bar) or SB 224,289 (SB; 10 mg/kg, i.p., gray bar) 30 minutes before the 2-hour session. They then received a treatment of either vehicle (Veh) or CP 94,253 (CP; 5.6 mg/kg, s.c.; black bar) 15 minutes prior to the test session that commenced under a VR5 schedule of reinforcement. Conditions were identical on the second test day for all rats except that the pretreatment given 30 minutes before session start was reversed such that rats that had received vehicle previously were given SB 224,289 and rats that had received SB 224,289 previously were given vehicle. Data are expressed as the mean (+ SEM). Asterisk (*) represents a difference from all other groups (Tukey’s posthoc test, P<.05).