Effects of profadol on operant behavior in the pigeon

The effects of profadol were determined on the key pecking of pigeons under the control of a multiple fixed-ratio, fixed-interval schedule of grain presentation. The effects of naloxone and pentobarbital on the behavioral suppression produced by profadol were also determined. Profadol (0.64-10 mg/kg) decreased responding under both schedule components, and the decrease in responding could not be reversed by either naloxone or pentobarbital. A moderate dose of profadol (1.25 mg/kg) was ineffective as an antagonist of morphine (20 mg/kg). Profadol does not produce its behavioral effects in pigeons by an action with a naloxone-sensitive opioid receptor and its non-opioid behavioral effects are dissimilar to those of previously studied meperidine-like phenylpiperidine analgesics.