Effects of perinatal exposure to aspartame on rat pups

Possible effects of perinatal exposure to L-aspartyl-L-phenylalanine methyl ester (aspartame) on rat pups were investigated. Adult female rats, and later their pups, were exposed, via their drinking water, to aspartame (0.007%, 0.036%, 0.18% or 0.9% w/v) or phenylalanine (0.45% w/v) for 12 days prior to conception until the pups were 38 days old. Control rats were given plain water. The adults exposed to aspartame consumed an average of 14, 68, 347 and 1614 mg/kg/day of aspartame and those exposed to phenylalanine consumed an average of 835 mg/kg/day of phenylalanine. After weaning the pups given aspartame consumed an average of 32, 154, 836, and 3566 mg/kg/day of aspartame and those given phenylalanine consumed an average of 1795 mg/kg/day of phenylalanine. No effect of aspartame or phenylalanine was detected on either two measures of morphological development (i.e., latencies to pinnae detachment and eye opening) or two tests of reflex development (i.e., latencies for surface righting at 7 days of age and negative geotaxis at 8 days of age). All groups were similar in spatial memory as assessed with two different mazes with pups 30-36 days old. The number of arms before reentry in an 8-arm radial-arm maze and the acquisition curves from a milk maze did not differ between groups. Furthermore, the latencies of mothers to retrieve their litters was also unaffected by the aspartame and phenylalanine. These results indicate that perinatal exposure to aspartame, when voluntarily consumed by mothers (14-1614 mg/kg/day) and later directly by the rat pups (32 to 3566 mg/kg/day) does not affect reflex development, morphological development or spatial memory.