Lead-induced behavioral impairment on a spatial discrimination reversal task in monkeys exposed during different periods of development.
A total of 52 monkeys (Macaca fascicularis) were dosed orally with vehicle or 1.5 mg/kg/day of lead on one of four dosing regimens (13 monkeys/group): Group 1, vehicle only; Group 2, dosed with lead from birth onward; Group 3, dosed with lead from birth to 400 days of age and vehicle thereafter; Group 4, dosed with vehicle from birth to 300 days of age and lead thereafter. Blood lead concentrations averaged 3-6 micrograms/dl when monkeys were not being dosed with lead, 32-36 micrograms/dl when being dosed with lead and having access to infant formula, and 19-26 micrograms/dl when being dosed with lead after weaning from infant formula. When monkeys were 7-8 years old, they were tested on three spatial discrimination reversal tasks: no irrelevant cues, irrelevant form cues, and irrelevant form and color cues. Fifteen reversals were run for each task. Only Group 2 was impaired in the absence of irrelevant cues, while all three treated groups were impaired in the presence of irrelevant cues. These results are in contrast to results from a series of nonspatial discrimination reversal tasks in these monkeys in which Groups 2 and 4 were impaired and Group 3 was unimpaired. The present results are in agreement with results from another spatial task, delayed alternation, in which all three treated groups were impaired.
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Toxicology Research Division, Bureau of Chemical Safety, Ottawa, Ontario, Canada.
D000375:Aging / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D005260:Female; D007854:Lead / Q000633:toxicity*; D007858:Learning / Q000187:drug effects; D008252:Macaca fascicularis / Q000254:growth & development*; D008297:Male; D013037:Spatial Behavior
D007854:Lead