TY  - JOUR
AU  - Cooper, Claire
AU  - Parthier, Daniel
AU  - Sibille, Jeremie
AU  - Tukker, Jan Johan
AU  - Tritsch, Nicolas
AU  - Schmitz, Dietmar
TI  - Ultraslow serotonin oscillations in the hippocampus delineate substates across NREM and waking.
JO  - eLife
VL  - 13
SN  - 2050-084X
CY  - Cambridge
PB  - eLife Sciences Publications
M1  - DZNE-2025-00847
SP  - RP101105
PY  - 2025
AB  - Beyond the vast array of functional roles attributed to serotonin (5-HT) in the brain, changes in 5-HT levels have been shown to accompany changes in behavioral states, including WAKE, NREM, and REM sleep. Whether 5-HT dynamics at shorter time scales can be seen to delineate substates within these larger brain states remains an open question. Here, we performed simultaneous recordings of extracellular 5-HT using a recently developed G-Protein-Coupled Receptor-Activation-Based 5-HT sensor (GRAB5-HT3.0) and local field potential in the hippocampal CA1 of mice, which revealed the presence of prominent ultraslow (<0.05 Hz) 5-HT oscillations both during NREM and WAKE states. Interestingly, the phase of these ultraslow 5-HT oscillations was found to distinguish substates both within and across larger behavioral states. Hippocampal ripples occurred preferentially on the falling phase of ultraslow 5-HT oscillations during both NREM and WAKE, with higher power ripples concentrating near the peak specifically during NREM. By contrast, hippocampal-cortical coherence was strongest, and microarousals and intracranial EMG peaks were most prevalent during the rising phase in both wake and NREM. Overall, ultraslow 5-HT oscillations delineate substates within the larger behavioral states of NREM and WAKE, thus potentially temporally segregating internal memory consolidation processes from arousal-related functions.
KW  - Animals
KW  - Serotonin: metabolism
KW  - Wakefulness: physiology
KW  - Mice
KW  - Hippocampus: physiology
KW  - Male
KW  - Mice, Inbred C57BL
KW  - CA1 Region, Hippocampal: physiology
KW  - Sleep
KW  - behavioral state (Other)
KW  - hippocampus (Other)
KW  - mouse (Other)
KW  - neuroscience (Other)
KW  - oscillation (Other)
KW  - ripples (Other)
KW  - serotonin (Other)
KW  - Serotonin (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:40643572
C2  - pmc:PMC12252544
DO  - DOI:10.7554/eLife.101105
UR  - https://pub.dzne.de/record/279880
ER  -