抄録
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 hrs during the daytime in prepro-orexin knockout mice (ORX-KO) and wild-type (WT) littermates. 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. Hypercapnic ventilatory response during QW in ORX-KO was significantly smaller than that in WT mice, 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 post-sigh sleep apneas were more frequent in ORX-KO than in WT littermates during both SWS and REM sleep. We concluded that orexin plays a crucial role both in CO2-sensitivity during wakefulness and in preservation of ventilation stability during sleep. [J Physiol Sci. 2007;57 Suppl:S214]
