Differences in stress reactivity between zebrafish with alternative stress coping styles

Area of Science:

• Comparative physiology
• Animal behavior
• Endocrinology

Background:

• Individual differences in stress responses define coping styles (proactive vs. reactive).
• Glucocorticoid (cortisol) response timing varies with stress coping styles, but data is limited.

Purpose of the Study:

• To investigate cortisol level differences between proactive and reactive zebrafish coping styles during stress response phases.
• To correlate cortisol levels with stress-related behaviors (depth preference, movement) across coping styles.

Main Methods:

• Zebrafish lines selectively bred for proactive and reactive coping styles were used.
• Whole-body cortisol levels and behavioral data (depth preference, movement) were quantified at different time points of the stress response (rise and recovery).

Main Results:

• Significant differences in cortisol levels and stress behaviors were observed between lines, sexes, and time points.
• Reactive zebrafish showed higher cortisol levels during the rising phase of the stress response compared to proactive zebrafish.
• Cortisol levels correlated with depth preference in the reactive line, but not the proactive line.

Conclusions:

• Cortisol level differences between stress coping styles are evident during the rising phase of the endocrine stress response.
• Cortisol levels may explain behavioral variations, such as depth preference, in reactive individuals.
• Timing and duration of cortisol release influence immediate behaviors and long-term neuromolecular adaptations.