NEONATAL RAPHE LESIONS INCREASE DOPAMINE FIBERS IN PREFRONTAL CORTEX OF ADULT RATS

IN order to characterize how the dopamine (DA) and serotonin (5HT) sys tems may be interacting in medial prefrontal cortex (mPFC) during post natal development, the specific toxin 5,7-dihydroxytryptamine (5,7-DHT ) was used to induce lesions of the nucleus raphe dorsalis (NRD) in ne onatal rats and the density of tyrosine hydroxylase-immunoreactive var icosities (TH-IRv) was assessed. During the early adult period, lesion ed rats showed a significant increase in the density of the TH-IR fibe rs in layers V and VI when compared with sham-treated animals. These r esults suggest that postnatal development in medial prefrontal cortex may be associated with a competitive interaction between cortical mono aminergic systems, such that an early disturbance in the development o f the 5HT innervation can potentially induce a hyperinnervation of DA fibres. (C) 1998 Rapid Science Ltd.