title: Serotonin and substance P colocalization in medullary projections to the nucleus tractus solitarius: dual-colour immunohistochemistry combined with retrograde tracing.
abstract: Serotonin (5HT) and substance P (SP) are colocalized in terminals within the nucleus tractus solitarius (NTS). The purpose of the present study was to determine the origin of these terminals. 5HT- and SP-immunoreactivities (IR) were visualized using dual-colour immunofluorescence histochemistry with amino-4-methylcoumarin-3-acetic acid- and fluorescein isothiocyanate-conjugated secondary antisera, while NTS-afferent neurons were visualized by retrograde labelling with rhodamine beads. Extensive colocalization of 5HT- and SP-IR was seen in NTS-afferent neurons located in the nucleus raphe pallidus, nucleus raphe obscurus, nucleus raphe magnus, and in the parapyramidal region. Over 80 per cent of the SP-IR NTS-afferent neurons contained 5HT-IR, while 68 per cent of the 5HT-IR neurons contained SP-IR. Thus, 5HT- and SP-IR are extensively colocalized in NTS-afferent neurons in the medullary raphe nuclei and associated areas of the ventral medulla.
authors: Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD.
authors: K B
authors: KB
authors: Thor
authors: C J
authors: CJ
authors: Helke
mesh_terms: D000818:Animals; D005455:Fluorescent Antibody Technique; D008297:Male; D008526:Medulla Oblongata / Q000032:analysis* / Q000166:cytology; D008863:Microspheres; D009475:Neurons, Afferent / Q000032:analysis; D051381:Rats; D012235:Rhodamines; D012701:Serotonin / Q000032:analysis*; D013373:Substance P / Q000032:analysis*
chemical_list: D012235:Rhodamines; D012701:Serotonin; D013373:Substance P