Neurons Provide Treatment Approach for Sleep Disorders

Falling asleep while driving or while operating the nuclear reactor might be a piece of entertainment when we see Homer Simpson (cartoon character). But in reality these disorders portray serious life challenges in the form of sleep-related illnesses – narcolepsy, cataplexy, and rapid eye movement (REM) sleep behavior disorder.

Neurons in the brain that link all three disorders were located in an area of the brain called the ventral medial medulla and received input from another area (sublaterodorsal tegmental nucleus, or SLD) too. These neurons can thus provide a target for treatments as per researchers at the University of Tsukuba.

‘The neurons that are involved in the REM sleep behvioral disorders like narcolepsy, cataplexy, or REM sleep behavior disorder are identified in the ventral medial medulla region of brain. They could serve as a good target for drug therapies for people with these disorders.’

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Sleep Disorders and the Neurons

Narcolepsy is characterized by suddenly falling asleep at any time during the day. Cataplexy is a related illness in which people suddenly lose muscle tone and collapse. Although they are awake, their muscles act as if they are in REM sleep.

During REM sleep, our eyes move back and forth, but our bodies remain still and we dream. This near-paralysis of muscles while dreaming is called REM-atonia, and is lacking in people with REM sleep behavior disorder.

Quiz on Sleep Disorder
The comfort of modern life comes at the cost of restful sleep! "Laugh and the world laughs with you, snore and you sleep alone-Anthony Burgess" Scientifically it is proven that a good night's sleep is imperative for maintaining a balance between the physical, emotional and behavioral well-being of a person.

People with REM sleep behavior disorder have their muscles move around, often going as far as to stand up and jump, yell, or punch. The team explored the neurons in the brain that normally prevent this type of behavior during REM sleep.

"The anatomy of the neurons we found matched what we know. They were connected to neurons that control voluntary movements, but not those that control muscles in the eyes or internal organs. Importantly, they were inhibitory, meaning that they can prevent muscle movement when active", says Professor Takeshi Sakurai, who led the study at the University of Tsukuba.

Blocking the input to these neurons in the mice models allowed them to move during their sleep, similar to someone with REM sleep behavior disorder. And thus, silencing the SLD-to-ventral medial medulla resulted in reduced number of cataplexic bouts.

Hence the study shows the role of the circuitry in controlling muscle atonia in both REM sleep and cataplexy.

Quiz on Narcolepsy
Narcolepsy is a chronic neurologic disorder that involves loss of brain's ability to regulate sleep and wake cycles normally. People having narcolepsy frequently sleep during the day as compared to those people who don't suffer from it. These sudden attacks of sleep can occur during any type of activity and at any time of the day. A normal sleep pattern involves the early stages of sleep then followed by deeper sleep stages and ultimately rapid eye movement (REM) sleep. In narcoleptic people, REM sleep occurs almost immediately in sleeping cycle and periodically during the waking hours.

Narcolepsy normally starts between ages of 15 and 25, but can become obvious at any age. In many cases, narcolepsy remains undiagnosed and hence untreated.

"The glycinergic neurons we have identified in the ventral medial medulla could be a good target for drug therapies for people with narcolepsy, cataplexy, or REM sleep behavior disorder. Future studies will have to examine how emotions, which are known to trigger cataplexy, can affect these neurons", says Sakurai.

Source-Medindia