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Either of two neuropeptide hormones synthesized in the hypothalamus that regulate sleep and wakefulness and whose dysfunction causes narcolepsy. Also called hypocretin.

[Greek orexis, appetite (from the view that orexin stimulates appetite; see anorexia) + -in.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


a hormone that promotes wakefulness and stimulates the appetite
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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* Orexin 2 receptor agonist TAK-925 received Sakigake Designation in Japan for treatment of narcolepsy.
A presentation on the additional analysis results from clinical phase II study of dual orexin receptor
Lemborexant acts on the orexin neurotransmitter system and is believed to regulate sleep and wake by controlling arousal without affecting awakening by external stimuli, and is being developed for the treatment of multiple sleep-wake disorders including insomnia disorder.
He oversaw clinical development of gene knockdown technology to evaluate novel antisense delivery approaches, worked on multiple teams that designed PET tracers to image therapeutic targets in the brain, and initiated a translational electroencephalogram sleep research lab that was instrumental in the discovery, development, and regulatory approval of Belsomra (suvorexant), a first-in-class orexin receptor antagonist, in both the United States and Japan.
From their observations, scientists found that disrupted sleep alters the levels of the hormone hypocretin, or orexin, in the brain, specifically the hypothalamus.
Optinose announced that it has entered into a license agreement with Inexia whereby Inexia has obtained certain rights that will enable the use of Optinose's exhalation delivery systems, or EDS, and other intellectual property in their effort to discover and develop novel therapies based on positive modulators of Orexin OX1 and OX2 for neurological diseases.
However, the new class of drugs called dual orexin receptor antagonists (DORAs) more selectively targeted the brain's sleep or wake pathways, which gives them safety advantages over benzodiazepines, said researchers from the Kagoshima University.
Orexin in patients with alcohol dependence treated for relapse prevention: A pilot study.
It also includes orexin neurons in the lateral hypothalamic area (LHA) and histaminergic neurons in the tuberomammillary nucleus (TMN).
Orexin is a neuropeptide released from the lateral hypothalamus to adjust food intake, sleep state, autonomous nervous system activity and basal metabolic rate.
The LH has 3 distinct populations of neurons: neurons that produce orexin, neurons that produce melanin-concentrating hormone (MCH), and neurons containing isoform 65 of glutamic acid decarboxylase (GAD65), named "GAD65 neurons."