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orexin (ORX),

Neuropeptide involved in neuroendocrine function including feeding and drinking behavior; two subtypes, A and B, exist.


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


A class of hypothalamic neuropeptide hormones that regulates sleep cycles and energy expenditure; they probably do not directly affect appetite, as was once believed.


One of a pair of centrally-acting neuropeptides produced by the lateral hypothalamus where the sensation of hunger is mediated. Rats given orexin will eat about ten times the normal amount of food and rats starved for 48 hours have more than twice the normal concentrations of orexin. There are also specific receptors for the two orexins. These facts are being exploited in the design of drugs that can both stimulate and reduce appetite.
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The experts think Thomas's orexin (a cell in the hypothalamus, which controls the sleep/wake function) was destroyed after a strep throat when the body had an autoimmune reaction and destroyed these cells,'' she said.
The drug competitively binds to two subtypes of orexin neuron receptors, interfering with orexin neurotransmission to facilitate sleep onset and maintenance.
The orexin neural system was discovered in the late 1990s, Dr.
Previous work by the group found that glucose blocks orexin cells (which was cited as a reason for after-meal sleepiness), and so the researchers also looked at interactions between sugar and protein.
Shin-ichiro Imai demonstrated that the protein sirtuin is required in order for calorie restriction to enhance the activity of orexin.
orexin, leptin) seem to function as establishing operations in promoting nicotine "craving" in smokers, and nicotine has been postulated to impact appetite (von der Goltz et al.
In the case of mammals, orexigenic activity of ghrelin is mediated by activation of other orexigenic peptides such as NPY, AgRP and orexin (Toshinai et al.
Suvorexant's mechanism of action in targeting the orexin system, which promotes wakefulness, sets it apart from some of the currently available sleep medications, according to Dr.
Scientists have found that a mixture similar to egg whites activated brain cells and triggered the release of a stimulant called orexin.
An upregulation of the activity of orexin neurons and changes in appetite regulating hormones may affect food intake.
Merck and Company is investigating a compound that inhibits the action of orexin receptors, which in turn interfere with the activity of orexin, a chemical in the brain that produces alertness.