Effects of dopaminergic drugs on food- and cocaine-maintained responding .4. Continuous cocaine infusions

The effects of cocaine (continuously infused during the session with and without a pre-loading dose) on responding maintained under multiple fixed-ratio 30 schedules of limited access to food and cocaine delivery (10 or 56 mu g/kg per injection) were studied in nine rhesus monkeys. When responding was maintained by 10 mu g/kg per injection, cocaine decreased rates of cocaine-maintained responding in a dose-related manner while having no effect on food-maintained responding. When responding was maintained by 56 mu g/kg per injection, cocaine decreased both cocaine- and food-maintained responding. These results show that the effects of continuous infusions of cocaine depend upon both the unit dose of cocaine and the event that maintains responding. As such, the effects of continuous infusions of cocaine are similar to those of other, longer-acting dopamine agonists. Such results support the development of long-acting agonist approaches to the pharmacotherapeutic treatment of cocaine abuse. (C) 1997 Elsevier Science Ireland Ltd.