The Retrotrapezoid Nucleus: Central Chemoreceptor and Regulator of Breathing Automaticity

Trends Neurosci. 2019 Nov;42(11):807-824. doi: 10.1016/j.tins.2019.09.002. Epub 2019 Oct 18.


The ventral surface of the rostral medulla oblongata has been suspected since the 1960s to harbor central respiratory chemoreceptors [i.e., acid-activated neurons that regulate breathing to maintain a constant arterial PCO2 (PaCO2)]. The key neurons, a.k.a. the retrotrapezoid nucleus (RTN), have now been identified. In this review we describe their transcriptome, developmental lineage, and anatomical projections. We also review their contribution to CO2 homeostasis and to the regulation of breathing automaticity during sleep and wake. Finally, we discuss several mechanisms that contribute to the activation of RTN neurons by CO2in vivo: cell-autonomous effects of protons; paracrine effects of pH mediated by surrounding astrocytes and blood vessels; and excitatory inputs from other CO2-responsive CNS neurons.

Keywords: brainstem; central respiratory chemoreception; hypercapnia; hypoxia; sleep apnea.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Carbon Dioxide / physiology
  • Chemoreceptor Cells / physiology*
  • Homeostasis
  • Humans
  • Hypercapnia / physiopathology
  • Hypoxia / physiopathology
  • Medulla Oblongata / physiology*
  • Neurons / physiology*
  • Respiration*
  • Sleep / physiology


  • Carbon Dioxide