Neonatal low-level lead exposure in monkeys: locomotor activity, schedule-controlled behavior, and the effects of amphetamine
Rice, D.C.; Gilbert, S.G.; Willes, R.F.
Toxicology and Applied Pharmacology 51(3): 503-513
1979
ISSN/ISBN: 0041-008X PMID: 120039 Document Number: 142947
Monkeys [Macaca fascicularis] were orally dosed with 500 .mu.g/kg per day of Pb as lead acetate from Day 1 of life. No overt signs of Pb toxicity were observed. At 2-3 yr of age, locomotor activity and performance on a multiple fixed interval 8 min-time out schedule of reinforcement were studied. On the fixed interval schedule, the 1st response after 8 min had elapsed resulted in delivery of fruit juice. Successive intervals were separated by time out periods, during which responses had no scheduled consequences. Treated monkeys behaved differently from controls during initial sessions of the multiple fixed interval-time out schedule, with exposure to Pb resulting in increased response rates, decreased median interresponse times, and more responding in the time out period. Subtle differences in the pattern of responding in the fixed interval persisted throughout the course of the study. There were no differences in locomotor activity between control and treated pairs of monkeys. There were no differential effects of d-amphetamine between treated and control monkeys on either locomotor activity or schedule-controlled behavior.