ORIGIN OF THE DOPAMINERGIC INNERVATION OF THE RAT DORSAL RAPHE NUCLEUS

THE aim of the present study was to describe the distribution of dopam ine (DA) fibres in the dorsal raphe nucleus (DRN) and to determine the ir neurones of origin. Using an anti-DA antibody, we observed a modera te density of DA varicose fibres over the DRN and a dense plexus of DA fibres in the ventrolateral central grey. With a sensitive retrograde tracing technique combining the use of cholera toxin subunit b with t yrosine hydroxylase immunohistochemistry, after tracer injections in t he DRN, a few double-labelled cells were observed in the ventral tegme ntal area and the A10 dorsocaudal DA cell group, as already described. In addition, a moderate number of double-labelled cells was seen in t he All hypothalamic DA cell group.