Schedule-controlled responding was maintained under multiple fixed-interval, fixed-ratio schedules in pigeons and single fixed-ratio schedules in mice. In pigeons, clonidine, an alpha 2-receptor agonist, produced dose-related decreases in responding under both fixed-interval and fixed-ratio schedules; fixed-interval responding was decreased at a lower dose than fixed-ratio responding. Low to in...

Drugs that decrease drug-maintained responding at doses that do not decrease other behaviors in animals may be suitable candidates for development as medications to treat drug abuse in humans. The present study examined whether this effect could be obtained with phentermine, a drug that has been reported to decrease cocaine intake in humans. Rhesus monkeys were trained under multiple fixed-rati...

In opioid-dependent subjects, the low-efficacy mu agonist nalbuphine generally precipitates withdrawal or withdrawal-like stimulus effects. To provide a more complete characterization of the discriminative stimulus effects of nalbuphine in opioid-treated subjects, seven White Carneux pigeons were treated daily with 10 mg/kg morphine i.m. and trained 6 h later to discriminate among 10 mg/kg morp...