Dopaminergic neurons in the nucleus raphe dorsalis innervate the prefrontal cortex in the rat: a combined retrograde tracing and immunohistochemical study using anti-dopamine serum.

The existence of a dopaminergic projection from the nucleus raphe dorsalis (RD) to the prefrontal cortex of the rat was demonstrated by combining immunohistochemistry with retrograde tracing. Injection of horseradish peroxidase or Fluoro-gold into the medial prefrontal cortex resulted in the appearance of retrogradely labelled neurons in the RD and in other brain regions. Some of these retrogradely labelled RD neurons were shown to be immunoreactive for dopamine. These data support the view that these dopaminergic RD neurons represent an extension of the A10 cell group.