TOLERANCE TO COCAINE RATE-INCREASING EFFECTS UPON REPEATED ADMINISTRATION

Four squirrel monkeys responded daily under a fixed-interval 5-min or 8-min schedule of food-pellet delivery. Cocaine (0.03 to 1.7 mg/kg) an d saline were injected before occasional daily sessions (acute adminis tration). Some doses of cocaine produced substantial overall increases in response rate for 3 of the subjects; effects were less substantial for the remaining subject, who exhibited modest increases in response rate early in the session and during the middle portion of the interv als. A dose that increased response rate when administered acutely was then administered before each session (chronic administration). Chron ic administration resulted in a reduction in the increases in response rate seen under acute administration for all subjects.