title: Substance P, tyrosine hydroxylase and serotonin terminals in the rat caudal nucleus ambiguus.
abstract: Substance P (SP), tyrosine hydroxylase (TH) and serotonin inputs onto laryngeal motoneurons (LMNs) are known to exist, but the distribution of their terminals in the caudal nucleus ambiguus (NA), remains unclear. Using immunofluorescence and confocal microscopy, we assessed simultaneously the distribution of SP, TH, serotonin and synaptophysin immunoreactive (ir) terminals in the caudal NA. SP, TH and serotonin-ir varicosities were considered to represent immunoreactive synapses if, using confocal microscopy, they were co-localized with the presynaptic protein, synaptophysin. Relative to the total number of synapses, we found only a modest number of SP, TH or serotonin-ir synaptic terminals in the caudal NA. The density of SP-ir synaptic terminals was higher than that of TH-ir and serotonin-ir synaptic terminals. Our results suggest that SP, TH, and serotonin-ir inputs may play only a modest role in regulating the activity of LMN. We conclude that SP, TH and serotonin are not always co-localized in terminals forming inputs with LMN and that they arise from separate subpopulations of neurons.
authors.affiliation: Australian School of Advanced Medicine, Macquarie University, NSW 2109, Australia.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Zhao
authors.forename: Qi-Jian
authors.initials: QJ
authors.lastname: Sun
authors.forename: Mandy S-Y
authors.initials: MS
authors.lastname: Lung
authors.forename: Debra
authors.initials: D
authors.lastname: Birch
authors.forename: Rui-Chen
authors.initials: RC
authors.lastname: Guo
authors.forename: Paul M
authors.initials: PM
authors.lastname: Pilowsky
mesh_terms: D000818:Animals; D008297:Male; D009046:Motor Neurons / Q000737:chemistry / Q000201:enzymology; D017729:Presynaptic Terminals / Q000737:chemistry* / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D014275:Trigeminal Caudal Nucleus / Q000737:chemistry* / Q000201:enzymology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D012701:Serotonin; D013373:Substance P; D014446:Tyrosine 3-Monooxygenase