Substance P, tyrosine hydroxylase and serotonin terminals in the rat caudal nucleus ambiguus

Wen Jing Zhao, Qi Jian Sun, Mandy S Y Lung, Debra Birch, Rui Chen Guo, Paul M. Pilowsky*

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Citations (Scopus)


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 sub-populations of neurons.

Original languageEnglish
Pages (from-to)337-340
Number of pages4
JournalRespiratory Physiology and Neurobiology
Issue number2
Publication statusPublished - 15 Sep 2011

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