Differential effects of ethanol on behavior and GABAA receptor subunit expression in zebrafish (Danio rerio) with alternative stress coping styles

Variation in stress responses between individuals is linked to factors ranging from stress coping styles to sensitivity of neurotransmitter systems. Many anxiolytic compounds (e.g. ethanol) can increase stressor engagement through modulation of neurotransmitter systems and are used to investigate stress response mechanisms. Here we assessed the role of the GABAA system on the variation of the behavioral stress response by comparing individuals differing in stress coping styles that were chronically treated with ethanol. Specifically, we investigated resulting changes in stress-related behavior and whole-brain GABAA receptor subunits (gabra1, gabra2, gabrd, & gabrg2) in response to a novelty stressor. There were significant main and interaction effects on two stress-related behaviors, where the ethanol-treated proactive individuals showed lower stress-related behaviors than their reactive counterparts. Proactive individuals showed significantly higher expression of gabra1, gabra2, and gabrg2 compared to reactive individuals and ethanol treatment resulted in upregulation of gabra1 and gabrg2 in both stress coping styles. These results show that differences in stress-related behaviors between stress coping styles may be facilitated in part by expression of select GABAA receptor subunits.