Oral phencyclidine (PCP) was established as a reinforcer and variables related to its reinforcing effects were studied. Liquid deliveries (0.5 ml) were contingent upon lip-contact responses on a solenoid-operated drinking spout, whereas delivery of food pellets was contingent on lever-pressing responses. The monkeys were food deprived at the start of the experiment. During the second hour of daily 3-hr sessions, food pellets were delivered according to a DRL (differential reinforcement of low rates) schedule; that is, only when lever-pressing responses were spaced 30-sec apart (DRL 30). Water was available from the drinking spout both during and between sessions. This procedure induced a high intake of water during the sessions. Subsequently, PCP (0.062 to 1 mg/ml) was available from the drinking spout during sessions while water was available between sessions. PCP intake ranged from 17 to 29.8 mg/kg and performance under the DRL schedule was disrupted. In the next phase of study, only PCP was available during the 3-hr sessions; water was available between sessions and the animals had limited access to food after each session. The number of lip-contact responses required for PCP delivery was varied from one to four. Maximum PCP intake ranged from 5.5 to 14.5 mg/kg. When only water was available, liquid deliveries during the session decreased, indicating that lip-contact responses had been maintained by PCP delivery. The effects of food deprivation and free access to food on liquid intake were also studied. Comparisons of PCP and water intake during alternate sessions indicated that when the monkeys had free access to food, PCP intake but not water intake decreased. Oral PCP served as a reinforcer over a range of concentrations and food deprivation enhanced this reinforcing effect.
|Number of pages
|Journal of Pharmacology and Experimental Therapeutics
|Published - Jan 1 1980