5-HT3 receptor-dependent modulation of respiratory burst frequency, regularity, and episodicity in isolated adult turtle brainstems.

Michelle E Bartman, Julia E R Wilkerson, Stephen M Johnson

Index: Respir. Physiol. Neurobiol. 172(1-2) , 42-52, (2010)

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Abstract

To determine the role of central serotonin 5-HT(3) receptors in respiratory motor control, respiratory motor bursts were recorded from hypoglossal (XII) nerve rootlets on isolated adult turtle brainstems during bath-application of 5-HT(3) receptor agonists and antagonists. mCPBG and PBG (5-HT(3) receptor agonists) acutely increased XII burst frequency and regularity, and decreased bursts/episode. Tropisetron and MDL72222 (5-HT(3) antagonists) increased bursts/episode, suggesting endogenous 5-HT(3) receptor activation modulates burst timing in vitro. Tropisetron blocked all mCPBG effects, and the PBG-induced reduction in bursts/episode. Tropisetron application following mCPBG application did not reverse the long-lasting (2h) mCPBG-induced decrease in bursts/episode. We conclude that endogenous 5-HT(3) receptor activation regulates respiratory frequency, regularity, and episodicity in turtles and may induce a form of respiratory plasticity with the long-lasting changes in respiratory regularity.Copyright 2010 Elsevier B.V. All rights reserved.