Impaired performance on odor-aversion testing following prenatal aspartame exposure in the guinea pig

Pregnant guinea pigs were administered aspartame (500 mg/kg) in sesame oil by gavage or sesame oil alone between the day of conception and parturition. A nontreated control group was also maintained. There were no statistically significant effects of the treatment on maternal weight gain, litter size, or birth weight of the pups. Newborn pups were weighed daily and on day 15 were injected with either LiCl or saline and placed in a cage with vanilla odor for 30 min. Twenty-four hr later the pups were permitted to choose between vanilla and lemon odors in a preference test. While both the vehicle-treated control and nontreated control groups injected with LiCl showed a conditioned aversion to vanilla, the aspartame-treated pups injected with LiCl did not. These data indicate that aspartame exposure at 500 mg/kg throughout gestation disrupts odor-associative learning in 15-day-old guinea pigs.