UNIMPAIRED LEARNING ABILITY OF RATS MADE ARTIFICIALLY PHENYLKETONURIC DURING FETAL OR NEONATAL LIFE.

Summary Rats made artificially phenylketonuria during fetal or early neonatal life by administration of large amounts of phenylalanine showed no defect in learning ability when tested later for capacity to acquire visual discrimination. Administration of large amounts of 5-HTP failed to correct the low brain serotonin concentrations characteristic of artificial phenylketonuria, The results of this investigation do not provide support for the theory that a serotonin deficiency in brain during infancy causes the mental defect characteristic of human phenylketonuria. In addition, it appears unlikely that the rat is a suitable experimental animal for exploring the exact mechanism of the mental defect of phenylketonuria in man.