Featured Research

from universities, journals, and other organizations

Brain mechanisms behind a debilitating sleep disorder

Date:
October 10, 2013
Source:
University of Toronto
Summary:
Cataplexy is characterized by muscle paralysis during cognitive awareness. Until now, researchers have not understood this condition well. Now research has shown that the neuro-degeneration of the brain cells that synthesize the chemical hypocretin causes the noradrenaline system to malfunction. When the norandrenaline system stops working properly, it fails to keep the motor and cognitive systems coupled. This results in cataplexy -- the muscles fall asleep but the brain stays awake.

Normally muscles contract in order to support the body, but in a rare condition known as cataplexy the body's muscles "fall asleep" and become involuntarily paralyzed. Cataplexy is incapacitating because it leaves the affected individual awake, but either fully or partially paralyzed. It is one of the bizarre symptoms of the sleep disorder called narcolepsy.

Related Articles


"Cataplexy is characterized by muscle paralysis during cognitive awareness, but we didn't understand how this happened until now, said John Peever of the University of Toronto's Department of Cell & Systems Biology. "We have shown that the neuro-degeneration of the brain cells that synthesize the chemical hypocretin causes the noradrenaline system to malfunction. When the norandrenaline system stops working properly, it fails to keep the motor and cognitive systems coupled. This results in cataplexy -- the muscles fall asleep but the brain stays awake."

Peever and Christian Burgess, also of Cell & Systems Biology used hypocretin-knockout mice (mice that experience cataplexy), to demonstate that a dysfunctional relationship between the noradrenaline system and the hypocretin-producing system is behind cataplexy. The research was recently published in the journal Current Biology in September.

The scientists first established that mice experienced sudden loss of muscle tone during cataplectic episodes. They then administered drugs to systematically inhibit or activate a particular subset of adrenergic receptors, the targets of noradrenaline. They were able to reduce the incidence of cataplexy by 90 per cent by activating noradrenaline receptors. In contrast, they found that inhibiting the same receptors increased the incidence of cataplexy by 92 per cent. Their next step was to successfully link how these changes affect the brain cells that directly control muscles.

They found that noradrenaline is responsible for keeping the brain cells (motoneurons) and muscles active. But during cataplexy when muscle tone falls, noradrenaline levels disappear. This forces the muscle to relax and causes paralysis during cataplexy. Peever and Burgess found that restoring noradrenaline pre-empted cataplexy, confirming that the noradrenaline system plays a key role.


Story Source:

The above story is based on materials provided by University of Toronto. Note: Materials may be edited for content and length.


Journal Reference:

  1. ChristianR. Burgess, JohnH. Peever. A Noradrenergic Mechanism Functions to Couple Motor Behavior with Arousal State. Current Biology, 2013; 23 (18): 1719 DOI: 10.1016/j.cub.2013.07.014

Cite This Page:

University of Toronto. "Brain mechanisms behind a debilitating sleep disorder." ScienceDaily. ScienceDaily, 10 October 2013. <www.sciencedaily.com/releases/2013/10/131010142926.htm>.
University of Toronto. (2013, October 10). Brain mechanisms behind a debilitating sleep disorder. ScienceDaily. Retrieved March 4, 2015 from www.sciencedaily.com/releases/2013/10/131010142926.htm
University of Toronto. "Brain mechanisms behind a debilitating sleep disorder." ScienceDaily. www.sciencedaily.com/releases/2013/10/131010142926.htm (accessed March 4, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Wednesday, March 4, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mom Triumphs Over Tragedy, Helps Other Families

Mom Triumphs Over Tragedy, Helps Other Families

AP (Mar. 3, 2015) After her son, Dax, died from a rare form of leukemia, Julie Locke decided to give back to the doctors at St. Jude Children&apos;s Research Hospital who tried to save his life. She raised $1.6M to help other patients and their families. (March 3) Video provided by AP
Powered by NewsLook.com
Looted and Leaking, South Sudan's Oil Wells Pose Health Risk

Looted and Leaking, South Sudan's Oil Wells Pose Health Risk

AFP (Mar. 3, 2015) Thick black puddles and a looted, leaking ruin are all that remain of the Thar Jath oil treatment facility, once a crucial part of South Sudan&apos;s mainstay industry. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
Woman Convicted of Poisoning Son

Woman Convicted of Poisoning Son

AP (Mar. 3, 2015) A woman who blogged for years about her son&apos;s constant health woes was convicted Monday of poisoning him to death by force-feeding heavy concentrations of sodium through his stomach tube. (March 3) Video provided by AP
Powered by NewsLook.com
Treadmill Test Can Predict Chance Of Death Within A Decade

Treadmill Test Can Predict Chance Of Death Within A Decade

Newsy (Mar. 2, 2015) Johns Hopkins researchers analyzed 58,000 heart stress tests to come up with a formula that predicts a person&apos;s chances of dying in the next decade. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins