Ethanol withdrawal-induced dysregulation of neurosteroid levels in plasma, cortex, and hippocampus in genetic animal models of high and low withdrawal.

Rationale: Endogenous γ-aminobutyric acid _A receptor (GABA _A R)-active neurosteroids (e.g., allopregnanolone) regulate central nervous system excitability and many physiological functions, so fluctuations are implicated in several neuropsychiatric disorders. Pertinently, evidence supports an inverse relationship between endogenous GABA _A R-active neurosteroid levels and behavioral changes in excitability during ethanol withdrawal (WD).
Objectives: The present studies determined mouse genotype differences in ten neurosteroid levels in plasma, cortex, and hippocampus over the time course of ethanol WD in the WD Seizure-Prone (WSP) and WD Seizure-Resistant (WSR) selected lines and in the DBA/2J (DBA) inbred strain.
Methods: Gas chromatography-mass spectrometry was utilized to simultaneously quantify neurosteroid levels from control-treated male WSP-1, WSR-1, and DBA mice and during 8 and 48 h of WD.
Results: Combined with our prior work, there was a consistent decrease in plasma allopregnanolone levels at 8 h WD in all three genotypes, an effect that persisted at 48 h WD only in DBA mice. WSR-1 and WSP-1 mice exhibited unexpected divergent changes in cortical neurosteroids at 8 h WD, with the majority of neurosteroids (including allopregnanolone) being significantly decreased in WSR-1 mice, but unaffected or significantly increased in WSP-1 mice. In DBA mice, hippocampal allopregnanolone and tetrahydrodeoxycorticosterone were significantly decreased at 8 h WD. The pattern of significant correlations between allopregnanolone and other GABA _A R-active neurosteroid levels differed between controls and withdrawing mice.
Conclusions: Ethanol WD dysregulated neurosteroid synthesis. Results in WSP-1 mice suggest that diminished GABA _A R function is more important for their high WD phenotype than fluctuations in neurosteroid levels.