Effects of an Orexin-2 Receptor Antagonist on Sleep and Event-Related Oscillations in Female Rats Exposed to Chronic Intermittent Ethanol During Adolescence

Background Alcohol use is on the rise among women in the United States which is especially concerning since women who drink have a higher risk of alcohol-related problems. Orexin (hypocretin) receptor antagonists may have some therapeutic value for alcohol-induced insomnia; however, the use of this class of drugs following female adolescent binge drinking is limited. The current study will address whether adolescent intermittent ethanol (AIE) in female rats can result in lasting changes in sleep pathology and whether orexin-targeted treatment can alleviate these deficits. Methods Following a 5-week AIE vapor model, young adult rats were evaluated on waking event-related oscillations (EROs) and EEG sleep. Subsequently, AIE rats were treated with orexin receptor 2 (OX2R) antagonist (MK-1064; 10, 20mg/kg) to test for modifications in sleep pathology and waking ERO. Results Female AIE rats exhibited lasting changes in sleep compared to controls. This was demonstrated by increased fragmentation of slow wave sleep (SWS) and rapid eye movement sleep, as well as reductions in delta and theta power during SWS. There was no impact of AIE on waking EROs. Acute MK-1064 hastened SWS onset and increased the number of SWS episodes, without increasing sleep fragmentation in AIE and controls. While treatment with MK-1064 did not impact sleep EEG spectra, waking ERO energy was increased in delta, theta, and beta frequency bands. Conclusions These results demonstrate that AIE can produce lasting changes in sleep in female rats, highly similar to what we previously found in males. Additionally, while the OX2R antagonist promoted sleep in both alcohol-exposed and unexposed rats, it did not reverse most of the alcohol-induced disruptions in sleep. Thus, OX2R antagonism may serve as a potential therapeutic strategy for the treatment of insomnia, but not the specific signs of alcohol-induced insomnia.