Opioid agonist and antagonist behavioural effects of buprenorphine

The agonist and antagonist effects of a range of bupenorphine doses (0.08–20 mg/kg) were studied on the responding of pigeons under a multiple fixed‐ratio, fixed‐interval schedule of grain presentation. Various doses (0.02–10 mg/kg) of buprenorphine were also tested in pigeons trained to discriminate between injections of 0.05 mg/kg of fentanyl and injections of distilled water. Buprenorphine, over a broad dose range (0.08–5 mg/kg), increased the rates of responding in the fixed‐interval component of the multiple schedule and disrupted patterning of responding within the fixed‐interval, without affecting fixed‐ratio responding even at a dose of 40 mg/kg. The effects of some of the high doses on fixed‐interval responding were still evident one and two days after buprenorphine injection. Doses of buprenorphine which produced increases in fixed‐interval responding were also effective as antagonists of the behavioural depression produced by 40 mg/kg of morphine, and were discriminated as fentanyl‐like by pigeons trained to discriminate between injections of fentanyl and injections of water. These results show that buprenorphine produces marked agonist and antagonist effects over an extremely broad dose range without producing behavioural depressant effects.