ACQUISITION OF ORAL PHENCYCLIDINE (PCP) SELF-ADMINISTRATION IN RHESUS-MONKEYS - EFFECTS OF DOSE AND AN ALTERNATIVE NONDRUG REINFORCER

The effects of drug dose and a non-drug alternative reinforcer on acqu isition of oral PCP self-administration in rhesus monkeys were examine d. Acquisition was studied using three groups of monkeys (seven subjec ts per group). One group received a low PCP dose (0.0375 mg/delivery) and the other two received a high PCP dose (0.15 mg/delivery). One of the high dose groups had concurrent access to a saccharin solution (0. 03% w/v) and water during the intersession (17.5-h) period. Food non-r estricted monkeys were initially given access to water under a fixed-r atio (FR) 1 schedule during daily 3-h sessions. Water was then replace d with PCP during the session. The monkeys were then reduced to 85% of their free-feeding body weights and fed before the session, and the F R value was increased from 1 to 2, 4 and 8. Subsequently, food was giv en post-session and water and PCP were available under concurrent FR 8 schedules. At this final step of the procedure, acquisition of PCP se lf-administration was considered to occur if PCP intake consistently e xceeded water intake. When all three groups were given concurrent acce ss to PCP and water, PCP intake was greater than water intake only in the group of monkeys receiving the high PCP dose. PCP intake increased when water replaced saccharin during intersession in the high PCP dos e group. Within-group data revealed that 85.7% of monkeys acquired PCP reinforcement in the group given access to the high PCP dose while on ly 42.8% acquired in the other two groups. These data suggest that dru g dose and presence of alternative non-drug reinforcers affect acquisi tion of drug self administration in non-human primates.