Vigilance state-dependent attenuation of hypercapnic chemoreflex and exaggerated sleep apnea in orexin knockout mice

Akira Nakamura, Wei Zhang, Masashi Yanagisawa, Yasuichiro Fukuda, Tomoyuki Kuwaki

Research output: Contribution to journalArticle

107 Scopus citations

Abstract

Exogenous administration of orexin can promote wakefulness and respiration. Here we examined whether intrinsic orexin participates in the control of breathing in a vigilance state-dependent manner. Ventilation was recorded together with electroencephalography and electromyography for 6 h during the daytime in prepro-orexin knockout mice (ORX-KO) and wild-type (WT) litter-mates. Respiratory parameters were separately determined during quiet wakefulness (QW), slow-wave sleep (SWS), or rapid eye movement (REM) sleep. Basal ventilation was normal in ORX-KO, irrespective of vigilance states. The hypercapnic ventilatory response during QW in ORX-KO (0.19 ± 0.01 ml·min-1·g-1·%CO2 -1) was significantly smaller than that in WT mice (0.38 ± 0.04 ml·min-1·g-1·%CO 2-1), whereas the responses during SWS and REM in ORX-KO were comparable to those in WT mice. Hypoxic responses during wake and sleep periods were not different between the genotypes. Spontaneous but not postsigh sleep apneas were more frequent in ORX-KO than in WT littermates during both SWS and REM sleep. Our findings suggest that orexin plays a crucial role both in CO2 sensitivity during wakefulness and in preserving ventilation stability during sleep.

Original languageEnglish (US)
Pages (from-to)241-248
Number of pages8
JournalJournal of applied physiology
Volume102
Issue number1
DOIs
StatePublished - Jan 1 2007

Keywords

  • Behavioral state control
  • Chemostimulation
  • Control of breathing
  • Hypothalamus

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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