SLDGABA neurons suppress wakefulness in healthy and narcoleptic mice, revealing a novel therapeutic target for narcolepsy.

The sleep-wake cycle is governed by intricate neural circuits, with the sublaterodorsal tegmental nucleus (SLD) being a known orchestrator of REM sleep. However, the specific contribution of its GABAergic neurons (SLDGABA) to overall sleep-wake regulation has remained elusive. Current treatments for narcolepsy, a chronic neurological condition characterized by overwhelming daytime sleepiness and cataplexy, often target orexin pathways or use stimulants, but a deeper understanding of underlying mechanisms and novel targets is needed.

Researchers investigated the role of SLDGABA neurons in sleep-wake regulation using both healthy (orexin+/+) and narcoleptic (orexin-/-) mouse models. They employed optogenetic silencing of SLDGABA neurons to observe its effect on wakefulness, and conversely, optogenetic activation of SLDGABA neurons to assess its impact on sleep states. The study also examined the anatomical projections of these neurons and their pathological role in narcoleptic mice, specifically observing effects on sleep attacks and cataplexy.

SLDGABA neurons were identified as key suppressors of wakefulness in both healthy and narcoleptic mice. Optogenetic silencing of these neurons in healthy mice rapidly induced robust wakefulness, accompanied by enhanced cortical and motor activity. Conversely, optogenetic activation of SLDGABA neurons suppressed wakefulness and promoted NREM sleep. Anatomical tracing confirmed SLDGABA axonal projections to known wake-promoting brain regions, providing a structural basis for their observed effects. Importantly, in orexin-deficient narcoleptic mice, activation of SLDGABA neurons triggered characteristic sleep attacks—rapid intrusions of NREM sleep during active wakefulness. > Silencing SLDGABA neurons in narcoleptic mice rescued animals from both sleep attacks and cataplexy, highlighting their pathological role in the disorder.