title: CSF orexin A concentrations and expressions of the orexin-1 receptor in rat hippocampus after cardiac arrest.
abstract: Orexins/hypocretins are neuropeptides that have various physiological effects, including the regulation of feeding behavior, neuroendocrine functions and sleep-wake cycles. Recent studies have suggested that the orexin system may also be involved in brain ischemic reactions. It is also known that changes in sleep patterns, energy homeostasis and neuroendocrine functions are often occur in neurological conditions associated brain ischemia. In the current study, we investigated the time-dependent changes in cerebrospinal fluid (CSF) orexin-A concentration and the expression of the orexin-1 receptor (OX1R) in the rat hippocampus after global ischemia-reperfusion (5 min cardiopulmonary arrest), which is known to induce delayed cell death in the CA1 region of the hippocampus. The CSF orexin-A concentration was elevated transiently at 24 h after ischemia. On days 2 and 4 after ischemia, CSF orexin concentrations were significantly reduced relative to the baseline, and returned to the baseline level by day 7. These changes were correlated with increased expression of OX1R in the CA1 on days 1 and 2 post-ischemia. These results suggest that dynamics of orexin signaling observed may have functional roles for neuronal damage associated with transient ischemia.
authors.affiliation: Department of Emergency and Critical Care Medicine, School of Medicine, Showa University, Shinagawa-ku, Tokyo, Japan. kdop@med.showa-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Dohi
authors.forename: Seiji
authors.initials: S
authors.lastname: Nishino
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nakamachi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ohtaki
authors.forename: Kentaro
authors.initials: K
authors.lastname: Morikawa
authors.forename: Takaaki
authors.initials: T
authors.lastname: Takeda
authors.forename: Seiji
authors.initials: S
authors.lastname: Shioda
authors.forename: Tohru
authors.initials: T
authors.lastname: Aruga
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D006323:Heart Arrest / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid*; D008297:Male; D009479:Neuropeptides / Q000134:cerebrospinal fluid*; D064446:Orexin Receptors; D000068797:Orexins; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide