Phenylketonuria in rats: reversibility of behavorial deficit.

Phenylketonuria was induced in hooded rats by the conventional procedure of feeding excessive quantities of L-phenylalanine after weaning. Although this procedure reliably induced large, dose-dependent deficits in performance on a water maze, the behavioral deficits were completely eliminated after cessation of phenylalanine loading. These results cast doubt on the assumption that this animal preparation adequately simulates the irreversible intellectual impairments found in the child with late-detected phenylketonuria.