Cholinergic inputs to laryngeal motoneurons functionally identified in vivo in rat: A combined electrophysiological and microscopic study

Tara G. Bautista, Qi Jian Sun, Wen Jing Zhao, Paul M. Pilowsky*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)

    Abstract

    The intrinsic laryngeal muscles are differentially modulated during respiration as well as other states and behaviors such as hypocapnia and sleep. Previous anatomical and pharmacological studies indicate a role for acetylcholine at the level of the nucleus ambiguus in the modulation of laryngeal motoneuron (LMN) activity. The present study investigated the anatomical nature of cholinergic input to inspiratory- (ILM) and expiratory-modulated (ELM) laryngeal motoneurons in the loose formation of the nucleus ambiguus. Using combined in vivo intracellular recording, dye filling, and immunohistochemistry, we demonstrate that LMNs identified in Sprague-Dawley rat receive several close appositions from vesicular acetylcholine transporter-immunoreactive (VAChT-ir) boutons. ELMs receive a significantly greater number of close appositions (mean ± standard deviation [SD]: 47 ± 11; n = 5) than ILMs (32 ± 9; n = 8; t-test P < 0.05). For both LMN types, more close appositions were observed on the cell soma and proximal dendrites compared to distal dendrites (two-way analysis of variance [ANOVA], P < 0.0001). Using fluorescence confocal microscopy, almost 90% of VAChT-ir close appositions (n = 45 boutons on n = 4 ELMs) were colocalized with the synaptic marker synaptophysin. These results support a strong influence of cholinergic input on LMNs and may have implications in the differential modulation of laryngeal muscle activity.

    Original languageEnglish
    Pages (from-to)4903-4916
    Number of pages14
    JournalJournal of Comparative Neurology
    Volume518
    Issue number24
    DOIs
    Publication statusPublished - 15 Dec 2010

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