TY - JOUR
T1 - Sex-specific hypnotic effects of the neuroactive steroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile are mediated by peripheral metabolism into an active hypnotic steroid
AU - Manzella, Francesca M.
AU - Cabrera, Omar H.
AU - Wilkey, Davis
AU - Fine-Raquet, Brier
AU - Klawitter, Jelena
AU - Krishnan, Kathiresan
AU - Covey, Douglas F.
AU - Jevtovic-Todorovic, Vesna
AU - Todorovic, Slobodan M.
N1 - Funding Information:
We then measured 3β-OH and 3α-OH concentrations in brain and liver at time to LORR after i.v. administration of 3β-OH. We observed no sex differences in 3β-OH concentrations in brain at time of LORR. The brain had notable concentrations of 3α-OH at time to LORR with no differences between males and females. However, 3β-OH concentrations were approximately seven-fold greater than 3α-OH concentrations and exceeded concentrations after i.p. administration in pharmacokinetic experiments (Fig 4c). At the time of LORR, the liver was producing large amounts of 3α-OH, but there were no sex differences for 3β-OH and 3α-OH. However, 3α-OH concentrations were higher than those of 3β-OH across all groups, indicating metabolism occurring early after 3β-OH administration (Fig 4d). These results support the hypothesis that sex differences in time to LORR may be mediated by peripheral metabolism of 3β-OH into 3α-OH.We found that the observed sex differences are directly related to sex-specific pharmacokinetic effects, specifically drug metabolism, as females produced more of the metabolite 3α-OH compared with males, indicating that sex differences in 3β–OH–induced hypnosis may be attributable to increased concentrations of 3α-OH. This is supported by studies showing that there were no sex differences in hypnotic effects or brain concentrations of 3β-OH or 3α-OH administered i.v. in time to LORR. Sex differences appear when measuring duration of LORR after sufficient time for drug metabolism has passed.3α-OH is a potent hypnotic, and lower doses of 3α-OH are required to achieve similar hypnotic effects as 3β-OH. The potent hypnotic effects of 3α-OH are likely attributable to its effect as a potent GABAA receptor modulator.7 Female mice do not convert 3α-OH to 3β-OH after administration of 3α-OH, supporting the conclusion that the hypnotic effects, at least in females, are solely attributable to 3α-OH. These results indicate that sex differences in 3β–OH–induced hypnosis may be caused by increased concentrations of its active metabolite 3α-OH.
Publisher Copyright:
© 2022 The Authors
PY - 2023/2
Y1 - 2023/2
N2 - Background: The novel synthetic neuroactive steroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH) blocks T-type calcium channels but does not directly modulate neuronal γ-aminobutyric acid type A (GABAA) currents like other anaesthetic neurosteroids. As 3β-OH has sex-specific hypnotic effects in adult rats, we studied the mechanism contributing to sex differences in its effects. Methods: We used a combination of behavioural loss of righting reflex, neuroendocrine, pharmacokinetic, in vitro patch-clamp electrophysiology, and in vivo electrophysiological approaches in wild-type mice and in genetic knockouts of the CaV3.1 T-type calcium channel isoform to study the mechanisms by which 3β-OH and its metabolite produces sex-specific hypnotic effects. Results: Adult male mice were less sensitive to the hypnotic effects of 3β-OH compared with female mice, and these differences appeared during development. Adult males had higher 3β-OH brain concentrations despite being less sensitive to its hypnotic effects. Females metabolised 3β-OH into the active GABAA receptor positive allosteric modulator (3α,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3α-OH) to a greater extent than males. The 3α-OH metabolite has T-channel blocking properties with sex-specific hypnotic and pharmacokinetic effects. Sex-dependent suppression of the cortical electroencephalogram is more pronounced with 3α-OH compared with 3β-OH. Conclusions: The sex-specific differences in the hypnotic effect of 3β-OH in mice are attributable to differences in its peripheral metabolism into the more potent hypnotic metabolite 3α-OH.
AB - Background: The novel synthetic neuroactive steroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH) blocks T-type calcium channels but does not directly modulate neuronal γ-aminobutyric acid type A (GABAA) currents like other anaesthetic neurosteroids. As 3β-OH has sex-specific hypnotic effects in adult rats, we studied the mechanism contributing to sex differences in its effects. Methods: We used a combination of behavioural loss of righting reflex, neuroendocrine, pharmacokinetic, in vitro patch-clamp electrophysiology, and in vivo electrophysiological approaches in wild-type mice and in genetic knockouts of the CaV3.1 T-type calcium channel isoform to study the mechanisms by which 3β-OH and its metabolite produces sex-specific hypnotic effects. Results: Adult male mice were less sensitive to the hypnotic effects of 3β-OH compared with female mice, and these differences appeared during development. Adult males had higher 3β-OH brain concentrations despite being less sensitive to its hypnotic effects. Females metabolised 3β-OH into the active GABAA receptor positive allosteric modulator (3α,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3α-OH) to a greater extent than males. The 3α-OH metabolite has T-channel blocking properties with sex-specific hypnotic and pharmacokinetic effects. Sex-dependent suppression of the cortical electroencephalogram is more pronounced with 3α-OH compared with 3β-OH. Conclusions: The sex-specific differences in the hypnotic effect of 3β-OH in mice are attributable to differences in its peripheral metabolism into the more potent hypnotic metabolite 3α-OH.
KW - calcium channels
KW - electroencephalogram
KW - metabolism
KW - neuroactive steroid
KW - pharmacokinetics
KW - sex-specific pharmacology
UR - http://www.scopus.com/inward/record.url?scp=85142502732&partnerID=8YFLogxK
U2 - 10.1016/j.bja.2022.09.025
DO - 10.1016/j.bja.2022.09.025
M3 - Article
C2 - 36428160
AN - SCOPUS:85142502732
SN - 0007-0912
VL - 130
SP - 154
EP - 164
JO - British journal of anaesthesia
JF - British journal of anaesthesia
IS - 2
ER -