Castillo-Ramírez, LA, Ryu, S and De Marco, RJ (2024) Cortisol dynamics and GR-dependent feedback regulation in zebrafish larvae exposed to repeated stress. Biology Open, 13 (10).

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Abstract

Zebrafish larvae show a rapid increase in cortisol in response to acute stressors, followed by a decline. While these responses are documented, both the duration of the refractory period to repeated stressors and the role of glucocorticoid receptors (GR) in specific phases of the glucocorticoid negative feedback are still being clarified. We explored these questions using water vortices as stressors, combined with GR blockage and measurements of whole-body cortisol in zebrafish larvae subjected to single and repeated stress protocols. Cortisol levels were elevated 10 min after stress onset and returned to baseline within 30-40 min, depending on the stressor strength. In response to homotypic stress, cortisol levels rose above baseline if the second stressor occurred 60 or 120 min after the first, but not with a 30-min interval. This suggests a rapid cortisol-mediated feedback loop with a refractory period of at least 30 min. Treatment with a GR blocker delayed the return to baseline and suppressed the refractory period, indicating GR-dependent early-phase feedback regulation. These findings are consistent with mammalian models and provide a framework for further analyses of early-life cortisol responses and feedback in zebrafish larvae, ideal for non-invasive imaging and high-throughput screening.

Item Type:	Article
Uncontrolled Keywords:	Animals; Zebrafish; Hydrocortisone; Receptors, Glucocorticoid; Larva; Stress, Physiological; Feedback, Physiological; Cortisol response; Glucocorticoid negative feedback; Glucocorticoid receptor antagonist; Refractory period; Zebrafish larvae; Animals; Zebrafish; Hydrocortisone; Receptors, Glucocorticoid; Larva; Stress, Physiological; Feedback, Physiological; 0699 Other Biological Sciences
Subjects:	Q Science > QH Natural history > QH301 Biology Q Science > QL Zoology
Divisions:	Biological and Environmental Sciences (from Sep 19)
Publisher:	The Company of Biologists
SWORD Depositor:	A Symplectic
Date Deposited:	11 Nov 2024 10:52
Last Modified:	11 Nov 2024 11:00
DOI or ID number:	10.1242/bio.061683
URI:	https://researchonline.ljmu.ac.uk/id/eprint/24728

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