Rice D C, Karpinski K F
Toxicology Research Division, Health and Welfare Canada, Ottawa, Ontario.
Neurotoxicol Teratol. 1988 May-Jun;10(3):207-14. doi: 10.1016/0892-0362(88)90019-0.
Cynomolgus monkeys (Macaca fascicularis) were dosed continuously from birth onward with 100, 50, or 0 micrograms/kg/day of lead. This resulted in blood lead concentrations of 25, 15, or 3 micrograms/dl respectively before withdrawal of infant formula at 200 days of age. Blood lead concentrations declined thereafter over the next 100-150 days to steady-state concentrations of 13, 11, or 3 micrograms/dl. At seven to eight years of age, monkeys were tested on a delayed alternation task. The task required the monkey to alternate responses between two pushbuttons; each alternation was rewarded with a small amount of apple juice. After each monkey learned the task, a delay was instituted between trials. The initial delay was 100 msec, and was increased in steps to 15 sec by the end of the experiment. Treated monkeys were impaired in their ability to learn the alternation task, but were not different from controls at short delay values (1 and 3 sec). At longer delay values (5 and 15 sec), treated monkeys again exhibited impairment. At the 15 sec delay value, some individuals in both treated groups exhibited marked perseveration, responding on the same button in some instances for hours at a time. Treated monkeys were also more variable in their performance across sessions than were controls. The data are interpreted as indicative of spatial learning and short-term memory deficits in the lead-exposed monkeys.
食蟹猴（猕猴）从出生起就持续接受100、50或0微克/千克/天的铅剂量。这导致在200日龄停止喂食婴儿配方奶粉之前，血铅浓度分别为25、15或3微克/分升。此后，血铅浓度在接下来的100 - 150天内下降至稳定浓度13、11或3微克/分升。在7至8岁时，对猴子进行延迟交替任务测试。该任务要求猴子在两个按钮之间交替做出反应；每次交替都会得到少量苹果汁作为奖励。每只猴子学会任务后，在试验之间设置延迟。初始延迟为100毫秒，到实验结束时逐步增加到15秒。接受治疗的猴子学习交替任务的能力受损，但在短延迟值（1和3秒）时与对照组没有差异。在较长延迟值（5和15秒）时，接受治疗的猴子再次表现出受损。在15秒延迟值时，两个治疗组中的一些个体表现出明显的持续性，有时会在同一个按钮上连续反应数小时。接受治疗的猴子在各次试验中的表现也比对照组更不稳定。这些数据被解释为表明铅暴露猴子存在空间学习和短期记忆缺陷。
