Orexins: a role in medullary sympathetic outflow.
Orexin A and B, also known as hypocretin 1 and 2, are two recently isolated hypothalamic peptides. As orexin-containing neurons are strategically located in the lateral hypothalamus, which has long been suspected to play an important role in feeding behaviors, initial studies were focused on the involvement of orexins in positive food intake and energy metabolism. Recent studies implicate a more diverse biological role of orexins, which can be manifested at different level of the neuraxis. For example, canine narcolepsy, a disorder with close phenotypic similarity to human narcolepsy, is caused by a mutation of hypocretin receptor 2 gene. Results from our immunohistochemical and functional studies, which will be summarized here, suggest that the peptide acting on neurons in the rostral ventrolateral medulla augment sympathoexcitatory outflow to the spinal cord. This finding is discussed in the context of increased sympathetic activity frequently associated with obesity.
Dun
N J
NJ
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, P.O. Box 70577, Johnson City, TN 37614, USA. dunnaec@etsu.edu
Le Dun
S
S
Chen
C T
CT
Hwang
L L
LL
Kwok
E H
EH
Chang
J K
JK
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002352:Carrier Proteins / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009479:Neuropeptides / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D002352:Carrier Proteins; C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos