BUPRENORPHINE-INDUCED ALTERATIONS OF COCAINE REINFORCING EFFECTS IN RHESUS-MONKEY - A DOSE-RESPONSE ANALYSIS

Buprenorphine reduces cocaine self-administration by rhesus monkeys, o piate- and cocaine-dependent men and polydrug abusers, but the mechani sms underlying these cocaine-opiate interactions are not well understo od. In the present study, the effects of daily placebo or buprenorphin e (0.1, 0.3 and 1.0 mg/kg) treatment on cocaine self-administration (0 .001-0.3 mg/kg/inject) were examined in five cocaine-experienced rhesu s monkeys. Saline and each of six cocaine doses were available in an i rregular order. Responding for cocaine (or saline) and food was mainta ined on a second order FR4 (VR 16:5) schedule of reinforcement. During placebo treatment, the daily number of cocaine injections increased a s the unit dose was increased and then decreased at higher doses. Coca ine doses that maintained the highest rates of responding during place bo treatment were more resistant to buprenorphine's effects. The typic al increase in response rate during the first five cocaine injections of a session also was attenuated by buprenorphine. The ascending limb of the cocaine dose-response curve was shifted downward and approximat ely one log unit to the right during low-dose buprenorphine treatment (0.1 mg/kg/day). In contrast, individual response rates for food pelle ts were unaffected, We conclude that buprenorphine selectively decreas es self-administration of some unit doses of cocaine at doses that hav e minimal effects on food-maintained responding.