Effects of naloxone and pentazocine on continuous shock-postponement responding by the pigeon.

The effects of pentazocine (3-30 mg/kg) and naloxone (3-100 mg/kg) were determined on the treadle-pressing behavior of pigeons under a schedule of shock postponement. Pentazocine increased the mean rate of responding at the 10 mg/kg dose, and greatly increased the mean shock rate at 30 mg/kg. Naloxone increased the mean response rate at all doses tested, without any increases in shock rates.