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.
"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.
Kim Luke | EurekAlert!
Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington
The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
17.08.2017 | Physics and Astronomy
17.08.2017 | Earth Sciences
17.08.2017 | Physics and Astronomy