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Low concentrations of nicotine increase frequency and decrease amplitude of respiratory bursts recorded from the hypoglossal nerve, with no change in amplitude of bursts recorded from the phrenic nerve, in the neonatal rat brainstem spinal cord preparation
Author(s) -
Wollman Lila Buls,
Flannigan Emily Gayle,
Fregosi Ralph Frank
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04638
Subject(s) - brainstem , nicotine , nicotinic agonist , excitatory postsynaptic potential , respiratory system , acetylcholine , hypoglossal nerve , inhibitory postsynaptic potential , anesthesia , cholinergic , phrenic nerve , spinal cord , endocrinology , medicine , neuroscience , chemistry , biology , receptor , tongue , pathology
Nicotinic acetylcholine receptors (nAChRs) are expressed throughout the central respiratory network, including postsynaptically on pattern generating neurons and motor neurons, and presynaptically on both excitatory and inhibitory inputs to these neurons. Normally, specific populations of nAChRs are briefly activated by the endogenous neurotransmitter acetylcholine, which is then rapidly hydrolyzed by acetylcholinesterase. However, with active or passive nicotine exposure, low circulating concentrations of nicotine results in global and prolonged activation of nAChRs, the effects of which are largely unknown. Here, we used the brainstem spinal cord preparation and rhythmic brainstem slice from nicotine‐naïve neonatal rats on postnatal days 1–4 to study the effects of prolonged, global nAChR activation on respiratory motor output. In the brainstem spinal cord preparation, bath application of 250 nM nicotine for 30 minutes resulted in an increase in respiratory burst frequency (21 % above baseline) accompanied by a decrease in hypoglossal nerve amplitude (62 % below baseline), but no change in phrenic nerve amplitude. In the rhythmic brainstem slice, bath application of nicotine concentrations as low as 50 nM caused an increase in frequency (35 % above baseline) and a decrease in amplitude (33 % below baseline) of respiratory bursts recorded from the hypoglossal nerve. These results indicate that low concentrations of nicotine are sufficient to cause changes in the respiratory network, including profound inhibition of hypoglossal motor output. Support or Funding Information 5R01HD071302‐07