Figure 2.
Effects of A2A receptor antagonists on self-administration of a THC dose (4 μg/kg per injection) that maintains maximum rates of responding under an FR10 schedule in squirrel monkeys. A, B, SCH-442416 (0.03–1 mg/kg, i.m.) significantly decreased the number of THC injections self-administered during 1 h sessions (A) and decreased overall response rates (B) (n = 5). C, D, KW-6002 (0.3 and 1 mg/kg, i.m.) significantly decreased the number of THC injections self-administered during the sessions (C) and decreased overall response rates (D) (n = 4). The number of THC injections per session (A, C) and overall response rates in the presence of the green light signaling THC availability (B, D) are shown over consecutive sessions. Each data point represents the mean ± SEM. *p < 0.05, **p < 0.01, planned comparisons with Holm correction versus the mean of the three sessions with vehicle pretreatment (sessions 1–3).