Serotonin elicits long-lasting enhancement of rhythmic respiratory activity in turtle brain stems in vitro

Stephen M. Johnson, Julia E R Wilkerson, Daniel R. Henderson, Michael R. Wenninger, Gordon S. Mitchell

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Brain stem preparations from adult turtles were used to determine how bath-applied serotonin (5-HT) alters respiration-related hypoglossal activity in a mature vertebrate. 5-HT (5-20 μM) reversibly decreased integrated burst amplitude by ∼45% (P < 0.05); burst frequency decreased in a dose-dependent manner with 20 μM abolishing bursts in 9 of 13 preparations (P < 0.05). These 5-HT-dependent effects were mimicked by application of a 5-HT1A agonist, but not a 5-HT1B agonist, and were abolished by the broad-spectrum 5-HT antagonist, methiothepin. During 5-HT (20 μM) washout, frequency rebounded to levels above the original baseline for 40 min (P < 0.05) and remained above baseline for 2 h. A 5-HT3 antagonist (tropesitron) blocked the post-5-HT rebound and persistent frequency increase. A 5-HT3 agonist (phenylbiguanide) increased frequency during and after bath application (P < 0.05). When phenylbiguanide was applied to the brain stem of brain stem/spinal cord preparations, there was a persistent frequency increase (P < 0.05), but neither spinal-expiratory nor -inspiratory burst amplitude were altered. The 5-HT3 receptor-dependent persistent frequency increase represents a unique model of plasticity in vertebrate rhythm generation.

Original languageEnglish (US)
Pages (from-to)2703-2712
Number of pages10
JournalJournal of applied physiology
Issue number6
StatePublished - 2001


  • 5-Hydroxytryptamine
  • Control of breathing
  • Plasticity
  • Reptile
  • Respiratory control
  • Rhythm generation

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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