Sex‐selective effects of prior binge‐like drinking followed by intermittent stress and ethanol drinking on alterations in several brain protein levels and neurosteroids

Abstract

Alcohol misuse and abuse are serious problems in our society and stress may increase the risk for escalation of drinking from recreational to problematic. We are continuing to explore the effect of prior binge drinking on subsequent drinking behaviors and the response to intermittent predator odor stress exposure, which is a model of traumatic stress. Adult male and female C57BL/6 mice had either 7 binge ethanol sessions (binge) or drank water (control). Following a 30‐day abstinence period, all mice were provided free access to 10% ethanol (10E) and water via lickometers for 4 weeks, with 30 min exposure to predator odor during the middle 2 weeks (2X/week). At 24 hrs after the final drinking session, mice were euthanized, and brains were harvested and frozen for Western Blot analyses vs separate naïve age‐matched mice. Dissected prefrontal cortex (PFC) and hippocampus (HIPP) were assayed for levels of the GABAA receptor a2 and a4 subunits, P450scc (an enzyme involved in steroidogenesis), and synaptophysin and ARC (activity‐regulated cytoskeletal protein), two proteins involved in synaptic plasticity. Western blot analyses found divergent responses across proteins and by sex. For the GABAA receptor a2 and a4 subunits, treatments (binge and control) decreased levels by 20–25% in male PFC but not HIPP versus naïve mice. Binge and control females displayed a similar decrease in PFC levels of the a4 subunit, whereas PFC levels of the a2 GABAA receptor subunit were increased by 25% compared to naïve mice. Additional sex differences were observed for the effect of the binge and control treatment groups versus naïve mice on P450scc levels: a 20% decrease in relative protein levels in male PFC versus a 15–30% increase in levels for both the female PFC and HIPP. Treatments also increased levels of synaptophysin in male and female HIPP by 20–30%, compared to naïve mice, with only the female PFC having a 30% increase in ARC levels. Alterations in relative protein levels were similar for the control and binge animals versus naïve mice, suggesting that the repeated predator odor stress and ethanol drinking had the greatest influence on assayed neuroaptations in the PFC and HIPP. Simultaneous analysis of ten plasma neurosteroid levels by gas chromatography‐mass spectrometry showed that treatment significantly increased levels of several GABAA receptor active neurosteroids in these male and female mice versus naïve animals. Taken together, these data reinforce the importance of assessing sex differences, as there were divergent neurochemical responses between males and females. These data also implicate the influence of neurosteroids on responses to the impact of prior binge‐like drinking on subsequent ethanol drinking and effects of stress.Support or Funding InformationSupported by BX001070 and BX002966 (DF) from the Department of Veteran AffairsThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.