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J Appl Physiol (1985). 2005 Apr;98(4):1387-95. Epub 2004 Nov 19.

Orexin stimulates breathing via medullary and spinal pathways.

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  • 1Dept. of Anatomy, Howard Univ. College of Medicine, 520 W St., NW, Washington, DC 20059, USA. jyoung@howard.edu

Abstract

A central neuronal network that regulates respiration may include hypothalamic neurons that produce orexin, a peptide that influences sleep and arousal. In these experiments, we investigated 1) projections of orexin-containing neurons to the pre-Botzinger region of the rostral ventrolateral medulla that regulates rhythmic breathing and to phrenic motoneurons that innervate the diaphragm; 2) the presence of orexin A receptors in the pre-Botzinger region and in phrenic motoneurons; and 3) physiological effects of orexin administered into the pre-Botzinger region and phrenic nuclei at the C3-C4 levels. We found orexin-containing fibers within the pre-Botzinger complex. However, only 0.5% of orexin-containing neurons projected to the pre-Botzinger region, whereas 2.9% of orexin-containing neurons innervated the phrenic nucleus. Neurons of the pre-Botzinger region and phrenic nucleus stained for orexin receptors, and activation of orexin receptors by microperfusion of orexin in either site produced a dose-dependent, significant (P <0.05) increase in diaphragm electromyographic activity. These data indicate that orexin regulates respiratory activity and may have a role in the pathophysiology of sleep-related respiratory disorders.

PMID:
15557013
[PubMed - indexed for MEDLINE]
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