Intravenously administered hypocretin-1 alters brain amino acid release: an in vivo microdialysis study in rats.

TitleIntravenously administered hypocretin-1 alters brain amino acid release: an in vivo microdialysis study in rats.
Publication TypeJournal Article
Year of Publication2003
AuthorsJohn, J, Wu M-F, Kodama T, Siegel JM
JournalThe Journal of physiology
Volume548
IssuePt 2
Pagination557-62
Date Published2003 Apr 15
ISSN0022-3751
KeywordsAmino Acids, Amygdala, Animals, Brain Chemistry, Carrier Proteins, Cerebellar Cortex, gamma-Aminobutyric Acid, Glutamic Acid, Injections, Intravenous, Intracellular Signaling Peptides and Proteins, Male, microdialysis, Neuropeptides, Rats, Rats, Sprague-Dawley
Abstract

We have reported that intravenous administration of hypocretin (Hcrt or orexin) reverses the symptoms of narcolepsy in genetically narcoleptic dogs. We have also reported that the onset of symptoms in canine genetic narcolepsy is accompanied by degenerative changes in forebrain regions, particularly the septal nucleus and amygdala. In the present in vivo microdialysis study we have investigated the effect of intravenous administration of Hcrt-1 (orexin-A) to anaesthetized rats on glutamate and GABA release in the amygdala, a region with moderate Hcrt innervation, and in the cerebellar cortex, a region with sparse or no Hcrt innervation. We found that intravenous Hcrt administration caused a marked (> 60 %) and sustained (> 50 min) increase in glutamate release within the amygdala, but no change in release in the cerebellar cortex. We did not detect a significant change in GABA release. When calcium-free artificial cerebrospinal fluid was used as the microdialysis perfusate, Hcrt-1 no longer produced an increase in glutamate release. Hcrt may act via the calcium-dependent regulation of glutamate release in certain nuclei of the central nervous system.

DOI10.1111/j.1365-2869.2012.01023.x
Alternate JournalJ. Physiol. (Lond.)