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Orexin - Wikipedia, the free encyclopedia The two highly-related peptides (orexin A and B, or hypocretin-1 and -2) are produced by cleavage of a single precursor protein. Studies suggest that orexin A/hypocretin-1 may be of greater biological importance than orexin B/hypocretin-2. GW649868 is under development by GSK for sleep disorders; it is an orexin antagonist. en.wikipedia.org /wiki/Orexin   (703 words)

Why we need a siesta after dinner - 05 June 2006 - New Scientist   (Site not responding. Last check: 2007-11-03) Burdakov’s team studied a group of brain cells called orexin neurons, which are found in the hypothalamus and produce proteins called orexins that are essential for maintaining normal wakefulness in humans. Burdakov’s team exposed orexin neurons to subtle changes in glucose levels similar to those that occur in the blood during daily cycles of eating and hunger, then measured their firing rate. Orexin neurons are known to help regulate appetite and metabolic rate, and when they become faulty this can trigger late-onset obesity. www.newscientist.com /article/dn9272.html   (572 words)

Turns of Phrase: Orexin orexins were injected into rats’; brains they became ravenous and ate anything up to ten times as much food as normal. It’s not entirely new: it had been previously applied at the end of the nineteenth century to a derivative of quinazolin which was thought for a while to be useful in increasing appetite. Of the hormones besides orexin that are believed to be factors in appetite, one is leptin, an appetite-suppressing protein made by fat-filled adipose cells. www.worldwidewords.org /turnsofphrase/tp-ore1.htm   (223 words)

Pfam 20.0 : Orexin   (Site not responding. Last check: 2007-11-03) Orexins (also known as hypocretins) are recently identified neuropeptides that are specifically localised to the hypothalamus. When applied to hypothalamic neurones, these peptides are neuroexcitatory, which action is probably mediated by their binding to a new family of G-protein-coupled receptors (orexin receptors 1 and 2), which were previously orphan PUBMED:9491897. To date, two orexins have been characterised (orexin-A and -B), both encoded by a single mRNA transcript (prepro-orexin): orexin-A is a 33-residue peptide with two intramolecular disulphide bonds in the N-terminal region; and orexin-B is a linear 28-residue peptide. pfam.wustl.edu /cgi-bin/getdesc?name=Orexin   (135 words)

Orexin's role in developing addiction   (Site not responding. Last check: 2007-11-03) Orexin is produced in the brain's lateral hypothalmus (LH) region. The team's demonstration of orexin's ability to counter cocaine-craving in mice suggests its promise in preventing cured addicts from relapsing to their drug habit, he adds. The discovery of orexin's molecular role explains why narcoleptic patients, whose LH neurons fail to produce normal amounts of the neuropeptide, rarely become addicted when medicated with amphetamines, in contrast to most people who receive the drugs. www.news-medical.net /?id=16029   (667 words)

BBC NEWS | Health | Sleep master chemical found Orexin is present in an area of the brain called the hypothalamus, an area responsible for controlling functions including body temperature and sleeping. This discovery could mean a drug based on orexin could be used to treat narcolepsy. And if such a drug could be created which had no side-effects, it could be used to help soldiers, surgeons and even shift-workers stay awake for days at a time. news.bbc.co.uk /2/hi/health/2664697.stm   (589 words)

Distinct Recognition of OX1 and OX2 Receptors by Orexin Peptides -- Ammoun et al. 305 (2): 507 -- Journal of ... C-Terminal Orexin-A Peptides Are Agonistic for the OX and OX Receptors. of the peptides inhibited subsequent response to orexin-A or orexin-A Orexin in the regulation of feeding and wakefulness. jpet.aspetjournals.org /cgi/content/full/305/2/507   (4591 words)

BBC - Science & Nature - Horizon - Living Nightmare On one set of X-ray pictures he found a chemical that seemed to be intimately connected with body weight: orexin. The orexin was not controlling obesity; it was dictating the animals' activity levels through their sleep patterns. Orexin has potential to become a lifechanging drug for narcoleptics. www.bbc.co.uk /science/horizon/2003/narcolepsy.shtml   (1015 words)

Orexin-A and Orexin-B Available from Peptides International Orexin-A is a 33-residue peptide with two intramolecular disulfide bonds, while orexin-B is a linear 28-residue peptide. Orexin-B was found to be 46% (13/28) identical in sequence to orexin-A. The primary structure of orexin-A is completely conserved among human, rat, mouse and bovine species. When orexin-A was administered intracerebroventricularly, food intake was stimulated in a dose-dependent manner within 1 hour. www.pepnet.com /orexin.html   (317 words)

University of Pennsylvania Health System: News and Periodicals: News Releases   (Site not responding. Last check: 2007-11-03) First, the activation of orexin neurons is related to preferences by the rats for cues associated with drug and food rewards. In addition, when the researchers administered a specific orexin antagonist, the initial learning of a drug preference and the reinstatement of extinguished drug-seeking behavior were blocked. Using rPP, a neuropeptide that activates orexin neurons in the lateral hypothalamus, the researchers were able to reinstate drug seeking in the rats formerly possessing extinguished drug-seeking behavior. www.uphs.upenn.edu /news/News_Releases/aug05/orexin.htm   (718 words)

Peptides that Regulate Food Intake: Orexin gene expression is increased during states of hypertriglyceridemia -- ... that genetic ablation of orexin neurons in mice causes hypophagia B: photomicrographs illustrate the increase in orexin cell density in the dorsal region of the PF of rats fed HFD vs. LFD. The density of cells expressing the orexin gene in the PF was strongly positively correlated with circulating triglycerides. ajpregu.physiology.org /cgi/content/full/284/6/R1454   (7717 words)

Orexins/Hypocretins, Orexin receptors antibodies (Orexin-A and Orexin-B) are a family of hypothalamic neuropeptides selectively expressed in the hypothalamus (1). Orexin-A and Orexin-B are derived from the same precursor (Prepro-orexin) by proteolytic cleavage. Orexin expression was detected in brain and to a small extent in testis (1). www.4adi.com /flr/orexin.html   (500 words)

Orexin-SAP Cells expressing orexin receptors have been implicated in sleep disorders such as narcolepsy. Orexin receptor expressing cells are eliminated with this reagent Behaviors associated with narcolepsy/cataplexy are greatly affected by the injection of orexin-SAP into the lateral hypothalamus of rats. www.atsbio.com /catalog/toxins/it20.html   (114 words)

Orexin-A Regulates Body Temperature in Coordination with Arousal Status -- Yoshimichi et al. 226 (5): 468 -- ... In this and succeeding figures, ``i3vt infusion'' represents that 15.0 nmol orexin-A or the same volume of PBS as controls was infused i3vt at 10:00 to 10:10 hr. i3vt infusion of 15.0 nmol orexin-A. In response to 15.0 nmol from orexin-A infusion and the concomitant elevation of ambulatory www.ebmonline.org /cgi/content/full/226/5/468   (4257 words)

Orexin A but Not Orexin B Rapidly Enters Brain from Blood by Simple Diffusion -- Kastin and Akerstrom 289 (1): 219 -- ... I-orexin A in the supernatant (parenchyma) or pellet (capillary) I-orexin A with and without 2 µg/mouse unlabeled orexin A in mice fasted for 22 h and their fed controls. I-orexin was not saturable, as shown by the lack of a decrease in its rate of entry after the simultaneous jpet.aspetjournals.org /cgi/content/full/289/1/219   (3330 words)

UniProtKB/Swiss-Prot entry O43612 [OREX_HUMAN] Orexin A broader role in the homeostatic regulation of energy metabolism, autonomic function, hormonal balance and the regulation of body fluids, is also suggested. Orexin-A binds to both OX1R and OX2R with a high affinity, whereas orexin-B binds only to OX2R with a similar high affinity. Orexins are absent and/or greatly diminished in the brain and cerebrospinal fluid (CSF) of most narcoleptic patients. www.expasy.org /uniprot/O43612   (526 words)

Orexin Neurons Express a Functional Pancreatic Polypeptide Y4 Receptor -- Campbell et al. 23 (4): 1487 -- Journal of ... a population of LHA neurons distinct from orexin. Beuckmann CT, Yanagisawa M (2002) Orexins: from neuropeptides to energy homeostatis and sleep/wake regulation. Horvath TL, Diano S, van den Pol AN (1999) Synaptic interaction between hypocretin (orexin) and neuropeptide Y cells in the rodent and primate hypothalamus: a novel circuit implicated in metabolic and endocrine regulations. www.jneurosci.org /cgi/content/full/23/4/1487   (6439 words)

Orexin stimulates breathing via medullary and spinal pathways -- Young et al. 98 (4): 1387 -- Journal of Applied ... Pressor effects of orexins injected intracisternally and to rostral ventrolateral medulla of anesthetized rats. Glucose regulates the release of orexin-A from the endocrine pancreas. Orexins: effects on behavior and localisation of orexin receptor 2 messenger ribonucleic acid in the rat brainstem. jap.physiology.org /cgi/content/full/98/4/1387   (4812 words)

Weight Regulation   (Site not responding. Last check: 2007-11-03) Moreover, the genes encoding the orexins were more than twice as active in food-deprived rats than in rats that had been fed freely. They have now developed a test for the human orexins that they hope will allow them to determine whether certain obese individuals make too much orexin, which, in turn, causes them to overeat. But the orexin story is likely to be as complicated as that of leptin, the appetite-dampening hormone produced by fat cells identified in 1995 by HHMI investigator Jeffrey Friedman of The Rockefeller University. www.hhmi.org /annual98/research/weight.html   (991 words)

The Orexin OX1 Receptor Activates a Novel Ca2+ Influx Pathway Necessary for Coupling to Phospholipase C -- Lund et al. ... Orexin-A response was also investigated in single cells under voltage-clamp conditions. orexin-A causes a Ca release as indicated by the fluorescence increase at the 340 nm, whereas no response is seen at 360 nm. At low orexin-A concentrations, both the Ca and IP responses required extracellular Ca The same was reflected in the assay of inositol phosphates. www.jbc.org /cgi/content/full/275/40/30806   (5677 words)

Orexins: Hungry Hormones The neuropeptides, or ligands, are called orexin-A and orexin-B. Their names, along with those for their associated receptors, OX1R and OX2R, derive from the Greek word orexis, for appetite. Graphic: Shows hypothalamic localization of neurons containing the novel neuropeptide orexin that regulate food intake behavior. The new research is expected to complement current knowledge of leptin and other proteins involved in appetite and obesity. www.accessexcellence.org /WN/SUA12/orexin298.html   (565 words)

A prepro-orexin gene polymorphism is associated with narcolepsy -- Gencik et al. 56 (1): 115 -- Neurology Orexin A and orexin B are both encoded by the prepro-orexin the orexin A and B are cleaved proteolytically. The sleep disorder canine narcolepsy is caused by a mutation in the hypocretin (orexin) receptor 2 gene. www.neurology.org /cgi/content/full/56/1/115   (1215 words)

Hypoglycemia Activates Orexin Neurons and Selectively Increases Hypothalamic Orexin-B Levels: Responses Inhibited by ... Photomicrographs showing Fos and orexin in neurons of the LHA in saline control (A) and in insulin-treated rats that were either hypoglycemic and freely fed (B) or hypoglycemic and fasted (C). Fos appears as green fluorescence in the nucleus, whereas orexin-A appears as red fluorescence in the cytoplasm. Hörvath TL, Diano S, van den Pol AN: Synaptic interaction between hypocretin (orexin) and neuropeptide Y cells in the rodent and primate hypothalamus: a novel circuit implicated in metabolic and endocrine regulations. diabetes.diabetesjournals.org /cgi/content/full/50/1/105   (4987 words)

Food deprivation differentially modulates orexin receptor expression and signaling in rat hypothalamus and adrenal ... Both bands appeared to be specific for orexin receptors, because when antibodies were preabsorbed with their respective blocking peptides (lanes 1 and 2 for rat adrenal and hypothalamus, respectively), there was no apparent immunodetection. Orexins, a novel family of hypothalamic neuropeptides, modulate pituitary luteinising hormone secretion in an ovarian steroid-dependent manner. Orexins stimulate corticosterone secretion of rat adrenocortical cells, through the activation of the adenylate cyclase-dependent signaling cascade. ajpendo.physiology.org /cgi/content/full/288/6/E1089   (6140 words)

Orexin.com :: Index   (Site not responding. Last check: 2007-11-03) This is the general forum for discussions that are of a general type and/or do not fit any of the other specified forums. This is the forum where discussions about orexin and narcolepsy are posted. This is the forum where discussions about orexin and sleep are posted. www.orexin.com   (132 words)

Expression of Orexin-A and Functional Orexin Type 2 Receptors in the Human Adult Adrenals: Implications for Adrenal ... 1998 Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behaviour. 1999 The sleep disorder canine narcolepsy is caused by a mutation in the hypocretin (orexin) receptor 2 gene. Orexin Excites GABAergic Neurons of the Arcuate Nucleus by Activating the Sodium--Calcium Exchanger jcem.endojournals.org /cgi/content/full/86/10/4808   (4079 words)

A role for lateral hypothalamic orexin neurons in reward seeking : Nature The orexins (or hypocretins) are neuropeptides recently identified as neurotransmitters in lateral hypothalamus neurons Here we show that activation of lateral hypothalamus orexin neurons is strongly linked to preferences for cues associated with drug and food reward. This reinstatement effect was completely blocked by prior administration of an orexin A antagonist. www.nature.com /nature/journal/v437/n7058/abs/nature04071.html   (307 words)

Low Plasma Orexin-A Levels Were Improved by Continuous Positive Airway Pressure Treatment in Patients With Severe ... Sakurai, T, Amemiya, A, Ishii, M, et al Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Sakurai, T Roles of orexins in the regulation of feeding and arousal. Kirchgessner, AL, Liu, M Orexin synthesis and response in the gut. www.chestjournal.org /cgi/content/full/127/3/731   (2939 words)

OX1 Orexin Receptors Couple to Adenylyl Cyclase Regulation via Multiple Mechanisms -- Holmqvist et al. 280 (8): 6570 -- ... Orexins are signal substances both in the central orexin-A. The elevation caused by orexin-A was concentration-dependent Concentration response curves for orexin-A and -B with respect to cAMP elevation (filled symbols) in intact CHO cells compared with similar data with respect to Ca elevation (empty symbols). www.jbc.org /cgi/content/full/280/8/6570   (5827 words)

Genomic Organization of Mouse Orexin Receptors: Characterization of Two Novel Tissue-Specific Splice Variants -- Chen ... Genomic Organization of Mouse Orexin Receptors: Characterization of Two Novel Tissue-Specific Splice Variants -- Chen and Randeva 18 (11): 2790 -- Molecular Endocrinology Genomic Organization of Mouse Orexin Receptors: Characterization of Two Novel Tissue-Specific Splice Variants Orexins also play an important physiological role in mend.endojournals.org /cgi/content/abstract/18/11/2790   (284 words)

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