Patients with pervasive developmental disorders, including autism, and attention-deficit hyperactivity disorder show behavioral hyperactivity during childhood. We investigated the effects of a neonatal 6-hydroxydopamine lesion on multiple gene expression in the rat striatum and midbrain. Spontaneous motor activity was significantly increased at 4-5 weeks of age. The animals were sacrificed, and the striatum and midbrain were subjected to gene expression profiling using a membrane array with 1176 kinds of cDNAs. Alterations were found in several classes of gene expression, depending on the brain region. Enhanced expression of the glutamate transporter gene was found in the striatum. Expression of the dopamine receptor D4 gene and dopamine transporter gene was also increased in the midbrain. These results suggest that 6-hydroxydopamine-treated rats may partly mimic human hyperkinesia not only in behavior but also in gene expression.