Morphological and behavioral effects of perinatal exposure to aspartame (Nutrasweet®) on rat pups

Possible side effects of perinatal exposure to L-aspartyl-L-phenylalanine methyl ester (aspartame) were studied by providing aspartame-containing water to female rats from 30 days before conception until the pups were 30 days of age. Compared with rat pups of mothers who drank plain water, aspartame-exposed pups were not different in morphological (i.e., pinnae detachment, eye opening, incisor eruption, and body weight) and reflex (i.e., surface righting and negative geotaxis) development. Additionally, no difference was found in the time taken by mothers to retrieve their litters. At 30 days of age, performance in a radial-arm maze of aspartame-exposed rats differed from that of rats not exposed to aspartame. Entries prior to repeat-that is, the number of arms chosen until an arm was reentered-was higher for the aspartame-exposed rats. Maze performance of rats exposed to aspartame for 30 days as adults did not differ from that of rats exposed only to water. These results suggest that aspartame may either facilitate the development of components involved in this procedure or reduce factors that interfere with this task.