Abstract
Variation in stress responses between individuals are 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. There are two alternative suites of correlated behavioral and physiological responses to stressors (stress coping styles) that differ in exploration tendencies: proactive and reactive stress coping styles. By chronically treating individuals differing in stress coping style with ethanol, a GABA-acting drug, we assessed the role of the GABAergic system on the behavioral stress response. Specifically, we investigated resulting changes in stress-related behavior (i.e. exploratory behavior) and whole-brain GABAA receptor subunits (gabra1, gabra2, gabrd, & gabrg2) in response to a novelty stressor. We found that 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 suggest that impacts of ethanol on stress-related behaviors vary by stress coping style and that expression of select GABAA receptor subunits may be one of the underlying mechanisms.
Highlights
Variation in stress responses between individuals are linked to factors ranging from stress coping styles to sensitivity of neurotransmitter systems
Examination of simple main effects revealed fish treated with 0.75% ethanol concentration showed an increase in time spent in the top half of the tank compared to 0.0% concentration for both the high-stationary behavior (HSB) and low-stationary behavior (LSB) line (HSB: p = 1.70 × 10–5; LSB: p = 0.003) with no drug-impaired locomotion
We showed significant main effects of line on anxiety-related behaviors and GABAAR subunit expressions where individuals with the proactive (LSB line) stress coping style had lower anxiety-related behaviors and higher expression of the α1, α2, and γ2-subunits relative to reactive (HSB line) individuals
Summary
Variation in stress responses between individuals are linked to factors ranging from stress coping styles to sensitivity of neurotransmitter systems. There are two alternative suites of correlated behavioral and physiological responses to stressors (stress coping styles) that differ in exploration tendencies: proactive and reactive stress coping styles. By chronically treating individuals differing in stress coping style with ethanol, a GABA-acting drug, we assessed the role of the GABAergic system on the behavioral stress response. Proactive individuals showed significantly higher expression of gabra[1], gabra[2], and gabrg[2] compared to reactive individuals and ethanol treatment resulted in upregulation of gabra[1] and gabrg[2] in both stress coping styles These results suggest that impacts of ethanol on stress-related behaviors vary by stress coping style and that expression of select GABAA receptor subunits may be one of the underlying mechanisms. Many studies have focused on acute effects of ethanol but relatively less is known on effects of chronic t reatment[14,30,49,54,55,56]
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