The distribution of serotonin, met-enkephalin and beta-lipotropin-like immunoreactivity in neuronal perikarya of the cat brainstem.

The distribution of methionine-enkephalin, serotonin and beta-lipotropin-containing neurones has been mapped immunohistochemically in the brainstem of the cat after local colchicine injections. Serotonin-containing neurons were found in th raphe in nucleus raph magnus (NRM), nucleus raphe pallidus (NRP) and nucleus raphe obscurus (NRO) and in a band extending cross the ventral reticular formation into nucleus paragigantocellularis lateralis (PGL) and nucleus lateralis reticularis (LRM). Enkephalin-positive cell bodies were also found in these raphe nuclei and in most divisions of the caudal reticular formation. Double labelling studies established that enkephalin and serotonin co-exist within some neurons in NRM and NRP. beta-Lipotropin-positive cell bodies were found principally within NRP and within the ventrolateral reticular formation in PGL and LRM.