ON THE RELATIONSHIP OF 5-HYDROXYTRYPTAMINE NEURONS TO 5-HYDROXYTRYPTAMINE 2A RECEPTOR-IMMUNOREACTIVE NEURONAL PROCESSES IN THE BRAIN-STEM OF RATS - A DOUBLE IMMUNOLABELING ANALYSIS

THE distribution of 5-MT,, receptor immunoreactivity in the brain stem was studied by means of a commercial 5-HT2A mouse monoclonal antibody against the N-terminal portion of the receptor (amino acids 1-72). Th e 5-HT2A immunoreactivity demonstrated in the nerve terminal or dendri tic-like structures of regions of the nucleus raphe pallidus, nucleus interfascicularis, motor nucleus of the trigeminal nerve, the ventral and dorsal tegmental nuclei and the median eminence by means of double immunofluorescence procedures were shown to be associated with 5-HT i mmunoreactive cell body-dendritic and/or nerve terminal structures. Be sides synaptic transmission the relationships are compatible with the existence of short distance volume transmission tin the mu m range) in 5-HT,A mediated 5-HT communication through terminal (5-HT)-terminal ( 5-HT,,) or soma/dendro (5-HT)-terminal (5-MT,,) and terminal (5-HT)-de ndritic (5-HT,A) interactions in discrete brain stem nuclei. NeuroRepo rt 9: 2505-2511 (C) 1998 Rapid Science Ltd.