Nomifensine-induced c-fos mRNA expression in discrete brain areas of the developing rat

In rats, the subcutaneous injection of a dopamine uptake inhibitor, nomifen sine (40 mg/kg), induced a significant increase in the c-fos mRNA levels in the neocortex on postnatal days 23 and 49, in the striatum on days 8, 14, 23 and 49, and in the hippocampus on day 23, when compared with saline admi nistration. The repeated injection with nomifensine (40 mg/kg once daily) f rom postnatal days 49 to 53 and from 23 to 27, but not from days 8 to 12 an d 14 to 18, resulted in an enhanced stereotypy response elicited by a subse quent challenge of the drug (5 mg/kg) 21 days after the last injection (beh avioral sensitization). The present results suggest that the neuronal circu its regulated by nomifensine might undergo regionally-different development al changes; which could be implicated in the development of behavioral expr essions including nomifensine-induced stereotypy sensitization. (C) 2001 El sevier Science Ireland Ltd. All rights reserved.