Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone

Neuroactive steroids (NAS) have long been recognized for their hypnotic and anesthetic properties in both clinical and preclinical settings. While sex differences in NAS sensitivity are acknowledged, the underlying mechanisms remain poorly understood. Here, we examined sex-specific responses to an e...

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Main Authors: Tamara Timic Stamenic, Ian Coulter, Douglas F. Covey, Slobodan M. Todorovic
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Biomolecules
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Online Access:https://www.mdpi.com/2218-273X/15/7/1033
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author Tamara Timic Stamenic
Ian Coulter
Douglas F. Covey
Slobodan M. Todorovic
author_facet Tamara Timic Stamenic
Ian Coulter
Douglas F. Covey
Slobodan M. Todorovic
author_sort Tamara Timic Stamenic
collection DOAJ
description Neuroactive steroids (NAS) have long been recognized for their hypnotic and anesthetic properties in both clinical and preclinical settings. While sex differences in NAS sensitivity are acknowledged, the underlying mechanisms remain poorly understood. Here, we examined sex-specific responses to an endogenous NAS epipregnanolone (EpiP) in wild-type mice using behavioral assessment of hypnosis (loss of righting reflex, LORR) and in vivo electrophysiological recordings. Specifically, local field potentials (LFPs) were recorded from the central medial thalamus (CMT) and electroencephalogram (EEG) signals were recorded from the barrel cortex. We found that EpiP-induced LORR exhibited clear sex differences, with females showing increased sensitivity. Spectral power analysis and thalamocortical (TC) and corticocortical (CC) phase synchronization further supported enhanced hypnotic susceptibility in female mice. Our findings reveal characteristic sex-dependent effects of EpiP on the synchronized electrical activity in both thalamus and cortex. These results support renewed exploration of endogenous NAS as clinically relevant anesthetic agents.
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spelling doaj-art-a1293c9c07f24c24bc6aebebe097acfa2025-08-20T03:08:10ZengMDPI AGBiomolecules2218-273X2025-07-01157103310.3390/biom15071033Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid EpipregnanoloneTamara Timic Stamenic0Ian Coulter1Douglas F. Covey2Slobodan M. Todorovic3Department of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USADepartment of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USADepartment of Developmental Biology, Washington University School of Medicine, Saint Louis, MO 63101, USADepartment of Anesthesiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USANeuroactive steroids (NAS) have long been recognized for their hypnotic and anesthetic properties in both clinical and preclinical settings. While sex differences in NAS sensitivity are acknowledged, the underlying mechanisms remain poorly understood. Here, we examined sex-specific responses to an endogenous NAS epipregnanolone (EpiP) in wild-type mice using behavioral assessment of hypnosis (loss of righting reflex, LORR) and in vivo electrophysiological recordings. Specifically, local field potentials (LFPs) were recorded from the central medial thalamus (CMT) and electroencephalogram (EEG) signals were recorded from the barrel cortex. We found that EpiP-induced LORR exhibited clear sex differences, with females showing increased sensitivity. Spectral power analysis and thalamocortical (TC) and corticocortical (CC) phase synchronization further supported enhanced hypnotic susceptibility in female mice. Our findings reveal characteristic sex-dependent effects of EpiP on the synchronized electrical activity in both thalamus and cortex. These results support renewed exploration of endogenous NAS as clinically relevant anesthetic agents.https://www.mdpi.com/2218-273X/15/7/1033neuroactive steroidshypnosiselectroencephalogramsex differencesgeneral anesthetics
spellingShingle Tamara Timic Stamenic
Ian Coulter
Douglas F. Covey
Slobodan M. Todorovic
Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
Biomolecules
neuroactive steroids
hypnosis
electroencephalogram
sex differences
general anesthetics
title Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
title_full Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
title_fullStr Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
title_full_unstemmed Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
title_short Electrophysiological Characterization of Sex-Dependent Hypnosis by an Endogenous Neuroactive Steroid Epipregnanolone
title_sort electrophysiological characterization of sex dependent hypnosis by an endogenous neuroactive steroid epipregnanolone
topic neuroactive steroids
hypnosis
electroencephalogram
sex differences
general anesthetics
url https://www.mdpi.com/2218-273X/15/7/1033
work_keys_str_mv AT tamaratimicstamenic electrophysiologicalcharacterizationofsexdependenthypnosisbyanendogenousneuroactivesteroidepipregnanolone
AT iancoulter electrophysiologicalcharacterizationofsexdependenthypnosisbyanendogenousneuroactivesteroidepipregnanolone
AT douglasfcovey electrophysiologicalcharacterizationofsexdependenthypnosisbyanendogenousneuroactivesteroidepipregnanolone
AT slobodanmtodorovic electrophysiologicalcharacterizationofsexdependenthypnosisbyanendogenousneuroactivesteroidepipregnanolone