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Lung respiratory rhythm and pattern generation in the bullfrog: Role of neurokinin-1 and u-opioid receptors

TitleLung respiratory rhythm and pattern generation in the bullfrog: Role of neurokinin-1 and u-opioid receptors
Publication TypeJournal Article
Year of Publication2009
AuthorsDavies, BL, Brundage, CM, Harris, MB, Taylor, BE
JournalJournal of Comparative Physiology B
Volume179
Pagination579–592
Abstract

Location of the lung respiratory rhythm generator(RRG) in the bullfrog brainstem was investigated byexamining neurokinin-1 and l-opioid receptor (NK1R,lOR) colocalization by immunohistochemistry and characterizingthe role of these receptors in lung rhythm andepisodic pattern generation. NK1R and lOR occurred inbrainstems from all developmental stages. In juvenilebullfrogs a distinct area of colocalization was coincidentwith high-intensity fluorescent labeling of lOR; highintensitylabeling of lOR was not distinctly and consistentlylocalized in tadpole brainstems. NK1R labelingintensity did not change with development. Similarity incolocalization is consistent with similarity in responses tosubstance P (SP, NK1R agonist) and DAMGO (lORagonist) when bath applied to bullfrog brainstems of differentdevelopmental stages. In early stage tadpoles andjuvenile bullfrogs, SP increased and DAMGO decreasedlung burst frequency. In juvenile bullfrogs, SP increasedlung burst frequency, episode frequency, but decreasednumber of lung bursts per episode and lung burst duration.In contrast, DAMGO decreased lung burst frequency andburst cycle frequency, episode frequency, and number oflung bursts per episode but increased all other lung burstparameters. Based on these results, we hypothesize thatNK1R and lOR colocalization together with a metamorphosis-related increase in lOR intensity marks the locationof the lung RRG but not necessarily the lung episodicpattern generator.

DOI10.1007/s00360-009-0339-3
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