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

• Published in: Respiratory physiology & neurobiology 2010-06, Vol.172 (1), p.42-52
• Main Authors: Bartman, Michelle E, Wilkerson, Julia E.R, Johnson, Stephen M
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Afferent Pathways - physiology; Animals; Biguanides - pharmacology; Biological and medical sciences; Dose-Response Relationship, Drug; Fundamental and applied biological sciences. Psychology; Hypoglossal Nerve - physiology; In Vitro Techniques; Indoles - pharmacology; Medical Education; Physical Stimulation - methods; Pulmonary/Respiratory; Receptors, Serotonin, 5-HT3 - physiology; Respiration - drug effects; Respiratory Center - cytology; Respiratory Center - physiology; Serotonin 5-HT3 Receptor Agonists; Serotonin 5-HT3 Receptor Antagonists; Serotonin Agents - pharmacology; Time Factors; Tropanes - pharmacology; Turtles - anatomy & histology; Vertebrates: respiratory system
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2010.04.008

Abstract To determine the role of central serotonin 5-HT3 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-HT3 receptor agonists and antagonists. mCPBG and PBG (5-HT3 receptor agonists) acutely increased XII burst frequency and regularity, and decreased bursts/episode. Tropisetron and MDL72222 (5-HT3 antagonists) increased bursts/episode, suggesting endogenous 5-HT3 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 (2 h) mCPBG-induced decrease in bursts/episode. We conclude that endogenous 5-HT3 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.