Regional differences in serotonergic input to canine parasternal intercostal motoneurons

Wen Zhi Zhan, Carlos B. Mantilla, Phillip Zhan, Asaf Bitton, Y. S. Prakash, Andre De Troyer, Gary C. Sieck

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

There is a mediolateral gradient in activation of the parasternal intercostal (PI) muscle during inspiration. In the present study, we tested the hypotheses that serotonergic [5-hydroxytryptamine (5-HT)] input from descending central drive and/or intrinsic size-related properties of PI motoneurons leads to the differential activation of PI muscles. In dogs, PI motoneurons innervating the medial and lateral regions of the PI muscles at the T3-T5 interspaces were retrogradely labeled by intramuscular injection of cholera toxin B subunit. After a 10-day survival period, PI motoneurons and 5-HT terminals were visualized by using immunohistochemistry and confocal imaging. There were no differences in motoneuron morphology among motoneurons innervating the medial and lateral regions of the PI muscle. However, the number of 5-HT terminals and the 5-HT terminal density (normalized for surface area) were greater in motoneurons innervating the medial region of the PI muscle compared with the lateral region. These results suggest that differences in distribution of 5-HT input may contribute to regional differences in PI muscle activation during inspiration and that differences in PI motoneuron recruitment do not relate to size.

Original languageEnglish (US)
Pages (from-to)1581-1589
Number of pages9
JournalJournal of applied physiology
Volume88
Issue number5
DOIs
StatePublished - May 2000

Keywords

  • Biogenic amines
  • Confocal microscopy
  • Immunohistochemistry
  • Neuromodulation
  • Respiratory muscles
  • Spinal cord

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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