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Cholinergic inputs to laryngeal motoneurons functionally identified in vivo in rat: A combined electrophysiological and microscopic study
Author(s) -
Bautista Tara G.,
Sun QiJian,
Zhao WenJing,
Pilowsky Paul M.
Publication year - 2010
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22495
Subject(s) - biology , nucleus ambiguus , cholinergic , vesicular acetylcholine transporter , neuroscience , acetylcholine , synaptophysin , anatomy , electrophysiology , interneuron , in vivo , choline acetyltransferase , immunohistochemistry , endocrinology , central nervous system , medulla oblongata , immunology , microbiology and biotechnology , inhibitory postsynaptic potential
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. J. Comp. Neurol. 518:4903–4916, 2010. © 2010 Wiley‐Liss, Inc.