IN order to characterize how the dopamine (DA) and serotonin (5HT) systems may be interacting in medial prefrontal cortex (mPFC) during postnatal development, the specific toxin 5,7-dihydroxytryptamine (5,7-DHT) was used to induce lesions of the nucleus raphe dorsalis (NRD) in neonatal rats and the density of tyrosine hydroxylase-immunoreactive varicosities (TH-IRv) was assessed. During the early adult period, lesioned rats showed a significant increase in the density of the THIR fibers in layers V and VI when compared with sham-treated animals. These results suggest that postnatal development in medial prefrontal cortex may be associated with a competitive interaction between cortical monoaminergic systems, such that an early disturbance in the development of the 5HT innervation can potentially induce a hyperinnervation of DA fibres.
1Laboratory for Structural Neuroscience, McLean Hospital, 115 Mill Street, Belmont, MA 02178, USA
2Department of Psychiatry, Harvard Medical School, Boston, MA; USA
3Program in Neuroscience, Harvard Medical School, Boston, MA; USA.
4Corresponding Author: Francine M. Benes
ACKNOWLEDGEMENTS: The authors wish to thank Ms Maureen Medeiros for her help in preparing this manuscript. This work has been supported by grants from the National Institute of Health (MH00423, MH42261) and the Stanley Foundation.
Received 6 March 1998; accepted 26 March 1998