Establishing models of corticosteroid patterns during the life history of killer whales (Orcinus orca) under human care

•Circadian rhythm influenced all circulating and excreted corticosteroids.•Sex was found to influence serum cortisol and fecal corticosterone metabolites.•Age influenced circulating glucocorticoids. The use of corticosteroids and their metabolites as a physiologic measure of stress in wildlife speci...

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Published in:General and comparative endocrinology 2021-01, Vol.301, p.113664-113664, Article 113664
Main Authors: Steinman, K.J., Robeck, T.R.
Format: Article
Language:English
Subjects:
Aldosterone
Feces
Glucocorticoids
Season
Serum
Sex
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Summary:•Circadian rhythm influenced all circulating and excreted corticosteroids.•Sex was found to influence serum cortisol and fecal corticosterone metabolites.•Age influenced circulating glucocorticoids. The use of corticosteroids and their metabolites as a physiologic measure of stress in wildlife species is increasing in both in and ex situ populations. However, factors such as season, circadian rhythm, sex and age are also known to influence corticosteroid production in wildlife. Our objective was to evaluate the influence of these variables on serum cortisol, corticosterone, aldosterone and their fecal metabolites in zoo-based killer whales (Orcinus orca). For evaluation of season, sex and age, we examined 30 animals (21 females, 9 males), and for circadian rhythm, we studied 18 animals (10 females, 8 males). Season did not influence corticosteroids (P ≥ 0.19). Circadian rhythm influenced all corticosteroids (P ≤ 0.012). Serum cortisol and corticosterone were highest in the morning and lower by mid-day and evening. Serum aldosterone was lowest during mid-day and highest in the evening. Excreted corticosteroid metabolites were higher in the morning and mid-day compared to evening (P ≤ 0.002). Serum cortisol was higher in males than females (P = 0.011). The inverse was observed for fecal corticosterone metabolites (P = 0.03). Serum corticosterone increased with age in all animals (P = 0.002), but serum cortisol increased with age in males only (P 
ISSN:0016-6480
1095-6840
DOI:10.1016/j.ygcen.2020.113664