Serotonergic retinopetal projections from the dorsal raphe nucleus in the mouse demonstrated by combined [H-3] 5-HT retrograde tracing and immunolabeling of endogenous 5-HT

The present study demonstrated a direct serotonergic retinopetal projection in the mouse stemming from the lateral portion of the dorsal raphe nucleus bilaterally. A double-labeling technique was employed combining: (1) radio autography and retrograde axonal tracing following intraocular injection of [H-3] 5-HT and (2) immunocytochemical identification of endogenous 5-HT. R adiolabeled neurons were only observed within the dorsal raphe nucleus and were always double-labeled with the 5-HT antibody. The radiolabeling appear ed to be specific resulting from the retrograde transport of a radioactive 5-HT derivative product following uptake of the neurotransmitter by intrare tinal terminals. (C) 2000 Elsevier Science B.V. All rights reserved.