Drinking patterns and alterations in several brain protein levels after binge drinking during adolescence followed by intermittent stress and ethanol drinking during adulthood in male and female C57BL/6J mice

Abstract

Alcohol abuse is a serious problem in our society with stress likely increasing the risk for escalation to harmful drinking. We are continuing to explore the effect of prior binge drinking on subsequent drinking behaviors and the response to intermittent predator odor stress (PS) exposure (a model of traumatic stress). We assessed responses in mice that were adolescent at the time of the binge drinking sessions, as we are aware that the adolescent brain is particularly vulnerable to ethanol. Male and female C57BL/6J adolescent mice had either 7 binge ethanol sessions (binge) or drank water (control). Following an abstinence period, all mice (now adults) were provided free access to 10% ethanol (10E) and water via lickometers for 4 weeks, with 30 min exposure to PS during the middle 2 weeks (2X/week). For mice exposed to the binge paradigm during adolescence, drinking levels changed across time after repeated PS. In males, ethanol intake increased over baseline by 34% in the binge group vs unchanged in the control group. In females, ethanol intake was increased by 57% (binge) and 38% (control) over baseline. At 24 hr after the final drinking session, brains were harvested and frozen for Western Blot analyses versus separate naïve age‐matched mice. Prefrontal cortex (PFC) and hippocampus (HIPP) were assayed for levels of the GABAA receptor (GABAAR) alpha2 and alpha 4 subunits, P450scc (a steroidogenesis enzyme), and CRF R1 (corticotropin releasing factor receptor) with values compared to naïve mice. We found divergent responses across proteins by sex and brain area. In male PFC, there reduced levels for GABAAR alpha 4 subunit levels (to 0.86 ± 0.04% for control and 0.85 ± 0.04% for binge vs naïve) and a decrease in P450scc levels of 084 ± 0.04% (control) and 0.89 ± 0.04% (binge) whereas the male HIPP also showed a trend towards reduced levels of the GABAAR alpha 4 subunit (0.90 ± 0.04% and 0.85 ± 0.03% for control and binge, respectively) but an increase in CRF‐R1 levels to 1.26 ± 0.05% for control and 1.28 ± 0.04% for binge. In contrast, the female PFC had decreased levels of the GABAAR alpha 2 subunit (0.77 ± 0.12% for control and 0.74 ± 0.07% for binge) with a similar decrease in alpha 4 subunit levels as in male PFC (0.84 ± 0.11% for control and 0.78 ± 0.09% for binge). Also similar to male, female HIPP had increased levels for CRF‐R1 levels of 1.14 ± 0.05% for control and 1.15 ± 0.05% for binge. And while P450scc levels were decreased (0.84 ± 0.04% for both groups) in female HIPP, a similar change was only observed in male PFC. The similar changes in the binge and control groups vs naïve animals suggest that the repeated PS and ethanol drinking history during adulthood influenced neuroadaptations in brain proteins more than the adolescent binge drinking experience. Taken together, these data continue to support the suggestion that a history of ethanol drinking and stress may interact to increase the risk for harm from subsequent drinking with important sex differences in drinking behaviors and brain protein changes.Support or Funding InformationSupported by BX001070 and BX002966 (DF) from the Department of Veteran AffairsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.