Behavioral effects of adenosine analogs in squirrel monkeys: relation to adenosine A2 receptors.

The behavioral effects of seven metabolically stable analogs of adenosine were studied in squirrel monkeys responding under a fixed-interval (FI) schedule of stimulus-shock termination. All drugs produced dose-related decreases in response rate, but differed in potency by up to three orders of magnitude. The 5'-carboxamide and 2-chlorine substituted analogs were more potent than the N6-substituted analogs. The potencies of the adenosine analogs in decreasing schedule-controlled behavior correlate well with their reported affinities for adenosine A2, but not A1, recognition sites as determined by displacement of bound ligands or modulation of adenylate cyclase activity. The results suggest that the behavioral effects of adenosine analogs in squirrel monkeys are linked to their actions at adenosine A2 receptors.