title: A serotonin-containing pathway from the area postrema to the parabrachial nucleus in the rat.
abstract: A combined retrograde tracing-immunofluorescent technique was used to identify the relationships between the cellular population projecting to the parabrachial nucleus and the serotonin-immunoreactive cell population of the area postrema in rats. The retrograde fluorescent tracer True Blue was injected in the parabrachial region and 3 days later the animals were perfused. Serial cryostat sections were processed for serotonin immunofluorescence. Three different groups of labeled cells were identified in the area postrema. First, True Blue-positive cells (up to 250/section) that project to the parabrachial nucleus were observed distributed throughout the area postrema. Second, in the pargyline (a monoamine oxidase inhibitor)-treated animals a large number of serotonergic cells (up to 125/section) was observed distributed throughout the area postrema. There was a tendency to a heavier distribution of serotonin-immunoreactive cells in the dorsal two-thirds of the area postrema. Third, double-labelled cells were also seen. Twenty percent of the True Blue-labelled cells projecting to the parabrachial nucleus were serotonin-immunoreactive. Thirty nine percent of the serotonin-immunoreactive population was retrogradely labelled with True Blue. Thus a new serotonergic pathway from the area postrema to the parabrachial nucleus is described; this pathway may be important in the ascending transmission and modulation of chemical and visceral sensory input.
authors.forename: A J
authors.initials: AJ
authors.lastname: Lança
authors.forename: D
authors.initials: D
authors.lastname: van der Kooy
mesh_terms: D000818:Animals; D005455:Fluorescent Antibody Technique; D008297:Male; D008526:Medulla Oblongata / Q000033:anatomy & histology / Q000378:metabolism*; D009490:Neurosecretory Systems / Q000033:anatomy & histology / Q000378:metabolism*; D011149:Pons / Q000033:anatomy & histology / Q000378:metabolism*; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D009435:Synaptic Transmission
chemical_list: D012701:Serotonin