© 1994 Oxford University Press
research-article |
In Utero Caffeine Exposure Affects Feeding Pattern and Variable Ratio Performance in Infant Monkeys
Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, Health Protection Branch, Health and Welfare Canada, Ottawa, Ontario Canada KIA 0L2
Received February 22, 1993; accepted August 2, 1993
Adult female monkeys (Macacafascicularis) were exposed via their drinking water to 0.0, 0.15, or 0.35 mg/ml of caffeine prior to and throughout pregnancy. Caffeine exposure resulted in a dose-related increase in the number of infant deaths at parturition. Additional females were added to the control group and the original groups were rebred, which resulted in 16, 13, and 9 live infants in control, low-dose, and high-dose groups, respectively. During pregnancy the mean serum caffeine levels were 3.4 and 10.3 µg/ml and the mean serum theophylline levels were 6.6 and 12.9 µg/ml for the low-dose and high-dose groups, respectively. Infants were separated from their mothers at birth and reared in a primate nursery to facilitate evaluation of infant performance on a variety of behavioral tasks. Infant formula consumption was monitored by a computer-based system 19 hr per day until 30 days of age. At 30 days of age infants were trained to press a button for a formula reward, after which they performed on a variable ratio schedule for a 14-day period. Monitoring of feeding pattern revealed that the treated infants spent significantly more time feeding than controls. On the variable ratio schedule, the high-dose group had consistently longer pause times and longer inter-response times than the control group. The results from this study indicate that in utero exposure to caffeine and its metabolites results in altered behavioral patterns in infant monkeys.