Bisphenol A causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity

We examined the effects of bisphenol A, an endocrine disruptor, on rat behavioral and cellular responses. Single intracisternal administration of bisphenol A (0.2‐20 μg) into 5‐day‐old male Wistar rats caused significant hyperactivity at 4–5 weeks of age. Rats were about 1.6‐fold more active in the nocturnal phase after administration of both 2 and 20 μg of bisphenol A than were control rats. The response was dose‐dependent. Based on DNA macroarray analyses of the midbrain, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. Furthermore, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. We conclude that bisphenol A affected central dopaminergic system activity, resulting in hyperactivity due most likely to a large reduction of tyrosine hydroxylase activity in the midbrain. © 2004 Wiley‐Liss, Inc.