Divergent Influence of Binge Drinking and Subsequent Intermittent Stress on Drinking Behaviors and Select Brain Protein Levels in Male and Female Mice

Alcohol misuse and abuse are serious problems in our society and stress may increase the risk for escalation of drinking from recreational to problematic. The present study explored the effect of prior binge drinking on subsequent drinking behaviors following 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 EtOH) or drank water (water group). 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 later Western Blot analyses vs separate naïve controls. Dissected prefrontal cortex (PFC) and hippocampus tissues were assayed for levels of CRF‐R1 (corticotropin releasing factor receptor 1), P450scc (an enzyme involved in steroidogenesis) and the GABA A receptor (GABA A R) alpha1 subunit. Whereas intermittent predator odor significantly increased anxiety‐like behaviors in male and female mice, measured on the elevated plus maze, it significantly increased 10E licks over baseline to a greater extent (78%) in the binge EtOH males versus the water males (27%). In contrast, females had no change in drinking following stress, regardless of prior binge drinking experience or not. Western blot analyses showed divergent responses across proteins and sex. In PFC, there were no significant differences between the binge EtOH and water groups. CRF‐R1 levels were unchanged across male or female groups, but there was a > 25% decrease in P450scc levels in males and a 20% increase in females, vs naïve controls. Levels for the GABA A R alpha1 subunit did not change in males but decreased by 20% in stressed females vs naïve. In contrast, male hippocampal tissue showed different responses between the stressed binge EtOH and water groups, vs naïve. CRF‐R1 levels were increased by 25% in water males with no change in binge EtOH animals. P450scc and GABA A R alpha1 subunit levels were unchanged in water groups but decreased by 13% and increased by 22% in the binge EtOH groups, respectively. Taken together, these data reinforce the importance of assessing sex differences as the synergistic effect of binge drinking and stress on alcohol intake occurred only in male mice. Additionally, the divergent neurochemical responses in males and females suggest that stress exerted the greatest effect in the PFC while binge EtOH exerted the greatest effect in the hippocampus. Support or Funding Information Supported by BX001070 and BX002966 (DF) from the Department of Veteran Affairs