[Ultrastructural relations between monoaminergic and peptidergic systems in the hypothalamus. Radioautographic approach and immunocytochemical binding in the arcuate nucleus and suprachiasmatic nucleus in the rat].

This paper deals with the cytological substratum for interactions between serotonin and dopamine, pro-opiomelanocortin (POMC) or vasoactive intestinal peptide (VIP) within the hypothalamus. Using a combination of radioautography and immunocytochemistry on the same thin sections in the rat, direct appositions not involving synaptic specializations were demonstrated between serotoninergic terminals and dopaminergic as well as POMC neurons in the arcuate nucleus. In the suprachiasmatic nucleus, quantitative data have indicated that VIP neurons constitute a preferential synaptic target for serotoninergic afferents. The functional implications of these results are discussed.