Data from: Maternal stress-associated cortisol stimulation may protect embryos from cortisol excess in zebrafish

Abnormal embryo cortisol level causes developmental defects and poor survival in zebrafish (Danio rerio). However, no study has demonstrated that maternal stress leads to higher embryo cortisol content in zebrafish. We tested the hypothesis that maternal stress-associated elevation in cortisol levels increases embryo cortisol content in this asynchronous breeder. Zebrafish mothers were fed cortisol-spiked food for 5 days, to mimic maternal stress, followed by daily breeding for 10-days to monitor temporal embryo cortisol content. Cortisol treatment increased mean embryo yield, but the daily fecundity were variable among the groups. Embryo cortisol content was variable in both groups over a 10 d period. A transient elevation in cortisol levels was observed in the embryos from cortisol fed mothers only on day 3, but not on subsequent days. We tested whether excess cortisol stimulates 11βHSD2 expression in ovarian follicles as a means to regulate embryo cortisol deposition. Cortisol treatment in vitro increased 11βHSD2 levels 7-fold, and this expression was regulated by actinomycin D and cyclohexamide suggesting tight regulation of cortisol levels in the ovarian follicles. We hypothesize that cortisol-induced upregulation of 11βHSD2 activity in the ovarian follicles is a mechanism restricting excess cortisol incorporation into the eggs during maternal stress.