OPIATE EFFECTS ON ISOLATION STRESS IN DOMESTIC-FOWL

In an attempt to examine the role of opioid system functioning in soci al attachment and isolation stress in young domestic fowl, the effects of morphine (5.0 mg/kg) and naloxone (5.0 mg/kg) were evaluated on di stress vocalizations, thermal nociception, thermoregulation, and respi ration following 15 min of isolation in 7-day-old White-Leghorn cocker els. Morphine decreased and naloxone increased distress vocalizations in isolated chicks. Isolation produced an increase in jump response la tencies (i.e., hypoalgesia) on a standard hot-plate test. In general, morphine decreased and naloxone increased mean jump latencies in both isolated and nonisolated chicks. Isolation produced an increase in cor e body temperature (i.e., hyperthermia); morphine decreased and naloxo ne increased core body temperatures independent of the isolation manip ulation. Social isolation did not affect respiration. However, morphin e depressed respiration in both isolated and nonisolated chicks. These results support the notion that opioid systems modulate social attach ment and isolation stress.