Suprachiasmatic Neuromedin-S Neurons Regulate Arousal

Overview

Journal bioRxiv

Date 2025 Mar 3

PMID 40027719

Authors

Yu-Er Wu

Roberto De Luca

Rebecca Y Broadhurst

Anne Venner

Lauren T Sohn

Sathyajit S Bandaru

Dana C Schwalbe

John Campbell

Elda Arrigoni

Patrick M Fuller

Affiliations

Soon will be listed here.

Abstract

Mammalian circadian rhythms, which orchestrate the daily temporal structure of biological processes, including the sleep-wake cycle, are primarily regulated by the circadian clock in the hypothalamic suprachiasmatic nucleus (SCN). The SCN clock is also implicated in providing an arousal 'signal,' particularly during the wake-maintenance zone (WMZ) of our biological day, essential for sustaining normal levels of wakefulness in the presence of mounting sleep pressure. Here we identify a role for SCN Neuromedin-S (SCN) neurons in regulating the level of arousal, especially during the WMZ. We used chemogenetic and optogenetic methods to activate SCN neurons in vivo, which potently drove wakefulness. Fiber photometry confirmed the wake-active profile of SCN neurons. Genetically ablating SCN neurons disrupted the sleep-wake cycle, reducing wakefulness during the dark period and abolished the circadian rhythm of body temperature. SCN neurons target the dorsomedial hypothalamic nucleus (DMH), and photostimulation of their terminals within the DMH rapidly produces arousal from sleep. Presynaptic inputs to SCN neurons were also identified, including regions known to influence SCN clock regulation. Unexpectedly, we discovered strong input from the preoptic area (POA), which itself receives substantial inhibitory input from the DMH, forming a possible arousal-promoting circuit (SCN->DMH->POA->SCN). Finally, we analyzed the transcriptional profile of SCN neurons via single-nuclei RNA-Seq, revealing three distinct subtypes. Our findings link molecularly-defined SCN neurons to sleep-wake patterns, body temperature rhythms, and arousal control.

References

Lein E, Hawrylycz M, Ao N, Ayres M, Bensinger A, Bernard A . Genome-wide atlas of gene expression in the adult mouse brain. Nature. 2006; 445(7124):168-76. DOI: 10.1038/nature05453. View

Lee I, Chang A, Manandhar M, Shan Y, Fan J, Izumo M . Neuromedin s-producing neurons act as essential pacemakers in the suprachiasmatic nucleus to couple clock neurons and dictate circadian rhythms. Neuron. 2015; 85(5):1086-102. PMC: 5811223. DOI: 10.1016/j.neuron.2015.02.006. View

Pierre-Ferrer S, Collins B, Lukacsovich D, Wen S, Cai Y, Winterer J . A phosphate transporter in VIPergic neurons of the suprachiasmatic nucleus gates locomotor activity during the light/dark transition in mice. Cell Rep. 2024; 43(5):114220. DOI: 10.1016/j.celrep.2024.114220. View

Brancaccio M, Enoki R, Mazuski C, Jones J, Evans J, Azzi A . Network-mediated encoding of circadian time: the suprachiasmatic nucleus (SCN) from genes to neurons to circuits, and back. J Neurosci. 2014; 34(46):15192-9. PMC: 4228128. DOI: 10.1523/JNEUROSCI.3233-14.2014. View

Butler A, Hoffman P, Smibert P, Papalexi E, Satija R . Integrating single-cell transcriptomic data across different conditions, technologies, and species. Nat Biotechnol. 2018; 36(5):411-420. PMC: 6700744. DOI: 10.1038/nbt.4096. View

Krout K, Kawano J, Mettenleiter T, Loewy A . CNS inputs to the suprachiasmatic nucleus of the rat. Neuroscience. 2002; 110(1):73-92. DOI: 10.1016/s0306-4522(01)00551-6. View

Moga M, Moore R . Organization of neural inputs to the suprachiasmatic nucleus in the rat. J Comp Neurol. 1997; 389(3):508-34. DOI: 10.1002/(sici)1096-9861(19971222)389:3<508::aid-cne11>3.0.co;2-h. View

Morin L . Neuroanatomy of the extended circadian rhythm system. Exp Neurol. 2012; 243:4-20. PMC: 3498572. DOI: 10.1016/j.expneurol.2012.06.026. View

Picelli S, Faridani O, Bjorklund A, Winberg G, Sagasser S, Sandberg R . Full-length RNA-seq from single cells using Smart-seq2. Nat Protoc. 2014; 9(1):171-81. DOI: 10.1038/nprot.2014.006. View

10.

Liao Y, Smyth G, Shi W . featureCounts: an efficient general purpose program for assigning sequence reads to genomic features. Bioinformatics. 2013; 30(7):923-30. DOI: 10.1093/bioinformatics/btt656. View

11.

Dijk D, Czeisler C . Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans. J Neurosci. 1995; 15(5 Pt 1):3526-38. PMC: 6578184. View

12.

Borbely A . A two process model of sleep regulation. Hum Neurobiol. 1982; 1(3):195-204. View

13.

Habib N, Li Y, Heidenreich M, Swiech L, Avraham-Davidi I, Trombetta J . Div-Seq: Single-nucleus RNA-Seq reveals dynamics of rare adult newborn neurons. Science. 2016; 353(6302):925-8. PMC: 5480621. DOI: 10.1126/science.aad7038. View

14.

Saper C . The central circadian timing system. Curr Opin Neurobiol. 2013; 23(5):747-51. PMC: 3758384. DOI: 10.1016/j.conb.2013.04.004. View

15.

Xie L, Xiong Y, Ma D, Shi K, Chen J, Yang Q . Cholecystokinin neurons in mouse suprachiasmatic nucleus regulate the robustness of circadian clock. Neuron. 2023; 111(14):2201-2217.e4. DOI: 10.1016/j.neuron.2023.04.016. View

16.

Pickard G . The afferent connections of the suprachiasmatic nucleus of the golden hamster with emphasis on the retinohypothalamic projection. J Comp Neurol. 1982; 211(1):65-83. DOI: 10.1002/cne.902110107. View

17.

Saper C, Fuller P, Pedersen N, Lu J, Scammell T . Sleep state switching. Neuron. 2010; 68(6):1023-42. PMC: 3026325. DOI: 10.1016/j.neuron.2010.11.032. View

18.

Todd W, Venner A, Anaclet C, Broadhurst R, De Luca R, Bandaru S . Suprachiasmatic VIP neurons are required for normal circadian rhythmicity and comprised of molecularly distinct subpopulations. Nat Commun. 2020; 11(1):4410. PMC: 7468160. DOI: 10.1038/s41467-020-17197-2. View

19.

Tanaka M, Ichitani Y, Okamura H, Tanaka Y, Ibata Y . The direct retinal projection to VIP neuronal elements in the rat SCN. Brain Res Bull. 1993; 31(6):637-40. DOI: 10.1016/0361-9230(93)90134-w. View

20.

Roh H, Tsai L, Lyubetskaya A, Tenen D, Kumari M, Rosen E . Simultaneous Transcriptional and Epigenomic Profiling from Specific Cell Types within Heterogeneous Tissues In Vivo. Cell Rep. 2017; 18(4):1048-1061. PMC: 5291126. DOI: 10.1016/j.celrep.2016.12.087. View