Combating Sleep Disorders: Scientists develop Novel Compound that regulates Wakefulness

Orexin image provided by researchers. Credit: Image courtesy of University of Tsukuba

A potent compound that promotes wakefulness and remedies the sleep disorder narcolepsy in model animals has been developed by a team of scientists. The compound works to mimic the action of a wake-promoting substance in our brain called “orexin.”.

Orexin, discovered in 1998 by Yanagisawa, is a neuropeptide that plays a central role in maintaining wakefulness. Its deficiency causes narcolepsy, in which patients experience excessive daytime sleepiness, often falling asleep uncontrollably. Patients also suffer from symptoms such as cataplexy (sudden loss of muscle tone triggered by emotion), vivid hallucinations when going into or out of sleep, and sleep paralysis. Orexin itself is proven to be effective in improving narcoleptic symptoms in model animals, but it cannot be readily used as a medicine because the blood-brain barrier (BBB) prevents it from entering the brain, where orexin works by binding to its receptors. Instead, a small molecule mimicking orexin (orexin receptor agonist) should be useful as a therapeutic agent for narcolepsy.

Nagase and his colleagues designed and synthesized more than 2,000 compounds, and eventually discovered the first non-peptidic orexin receptor agonist, YNT-185. Giving YNT-185 to normal mice strongly promoted wakefulness. Moreover, YNT-185, when given to narcoleptic model mice, significantly ameliorated the symptom (unpublished data). This achievement is an important first step for development of a novel medicine to correct the fundamental disease mechanism of narcolepsy. http://www.tsukuba.ac.jp/english/attention-research/p201511181038.html