Effect of 5-hydroxytryptamine on vagal C-fiber subtypes in guinea pig lungs

Benjamas Chuaychoo, Min Goo Lee, Marian Kollarik, Bradley J. Undem

Research output: Contribution to journalArticle

Abstract

5-Hydroxytryptamine (5-HT, serotonin) evokes pulmonary reflexes partially by activating vagal bronchopulmonary C-fibers. In the guinea pig, vagal bronchopulmonary C-fibers arise from cell bodies situated in the nodose and the jugular ganglia. The nodose and the jugular C-fibers differ both pharmacologically and neurochemically, and may subserve different functions. In this study, we compared the effect of 5-HT on the nodose and jugular C-fibers with receptive fields within the guinea pig lungs. The nerve terminals of the vagal bronchopulmonary C-fibers were studied in an ex vivo isolated perfused lung nerve preparation using the extracellular recordings. All nodose C-fibers responded to transient administration of 5-HT (10 μM) and to the selective 5-HT3 receptor agonist, 2-methyl-5-HT (10 μM), with the action potential discharge. The selective 5-HT3 receptor antagonist ondansetron (10 μM) inhibited (by ∼90%) the activation of the nodose C-fibers evoked by 5-HT (10 μM). In contrast to the nodose C-fibers, the jugular C-fibers were unresponsive or poorly responsive to 5-HT (n=9) and unresponsive to 2-methyl-5-HT (n=11). A direct action of 5-HT on the C-fiber neurons was supported using the whole cell patch clamp recordings from the isolated vagal sensory neurons retrogradely labeled from the lungs. Consistently with the studies on the nerve terminals, 5-HT (10 μM) induced inward current in nodose lung-specific capsaicin-sensitive neurons. Conversely, 5-HT was inefficient to stimulate the lung-specific jugular neurons. We conclude that in the guinea pig lungs, 5-HT selectively stimulates vagal nodose, but not jugular C-fibers via the 5-HT3 receptors in the neuronal membrane.

Original languageEnglish (US)
Pages (from-to)269-276
Number of pages8
JournalPulmonary Pharmacology and Therapeutics
Volume18
Issue number4
DOIs
StatePublished - Aug 2005

Keywords

  • 5-Hydroxytryptamine
  • Afferent
  • C-fiber
  • Guinea pig
  • Lung
  • Nodose ganglion
  • Ondansetron
  • Vagus nerve

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Biochemistry, medical
  • Pharmacology (medical)

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