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REM sleep is the stage associated with dreaming, memory consolidation, and emotional regulation. The MT1 receptor affects noradrenergic neurons located in a brain region called the locus coeruleus (which means "blue spot" in Latin). During REM sleep, these neurons remain inactive. There is a connection between disturbances in REM sleep and certain serious diseases—such as Parkinson's disease and Lewy body dementia—against which no effective treatments are currently available.
"Not only does this discovery help us better understand the mechanisms of sleep, but its clinical potential is highly encouraging," said Gabriella Gobbi, lead researcher of a new study published in the Journal of Neuroscience. Dr. Gobbi, a professor of psychiatry at McGill University, is a clinician-researcher at the McGill University Health Centre Research Institute and holds the Canada Research Chair in Therapeutics for Mental Health.
The science of sleep
In humans, sleep consists of alternating cycles of slow-wave sleep and REM sleep, each performing a well-defined physiological function: REM sleep plays a key role in memory consolidation and emotional regulation, while slow-wave sleep is when the body recovers and regenerates. Disruption of this cycle can deteriorate cognitive functions and increase the vulnerability to neuropsychiatric disorders.
Until now, scientists had been unable to pinpoint the exact receptor that triggers REM sleep. This new study reveals that the MT1 melatonin receptor plays a significant role in regulating this phase of sleep. Using a novel drug targeting the MT1 receptor, the research team managed to extend REM sleep in animals while reducing neuronal activity.
"Currently, there are no medications that specifically target REM sleep. Most hypnotics on the market increase total sleep duration but tend to impair REM sleep," explains Prof. Stefano Comai, co-lead author of the study, professor at the University of Padua and associate professor at McGill University.
The researchers believe that further study of the neurobiological and pharmacological aspects of REM sleep is needed to design targeted treatments that could improve the quality of life for individuals affected by these debilitating diseases. There is every reason to hope that this exploration of the complex mechanisms regulating sleep will lead to the development of effective interventions for neurological disorders.
The article "Selective enhancement of REM sleep in male rats through activation of MT1 receptors located in the locus coeruleus norepinephrine neurons," by Martha López-Canul, Stefano Comai, Gabriella Gobbi, et al., was published in the Journal of Neuroscience on July 17, 2024.