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Research article2012Peer reviewedOpen access

Cortisol and corticosterone independence in cortisol-dominant wildlife

Koren Lee, Whiteside Douglas, Fahlman Asa, Ruckstuhl Kathreen, Kutz Susan, Checkley Sylvia, Dumond Mathieu, Wynne-Edwards Katherine


Species have traditionally been defined as cortisol-dominant or corticosterone-dominant, depending on the glucocorticoid that is reported. To assess the degree of covariance versus independence between cortisol and corticosterone, 245 serum samples belonging to 219 individuals from 18 cortisol-dominant, non-domesticated species (6 mammalian orders) were compared by mass spectrometry. In these samples, which were elevated above baseline, concentration ranges were overlapping for cortisol and corticosterone although cortisol was dominant in every sample except one of 17 bighorn sheep with a corticosterone-biased cortisol-to-corticosterone ratio of 0.17. As expected, cortisol and corticosterone were strongly associated among species (r(2) = 0.8; species with high absolute cortisol tend to have high absolute corticosterone concentrations), with wide variation in the species-average cortisol-to-corticosterone ratio (range 7.5-49) and an even wider ratio range across individuals (0.2-341). However, only 9 out of 13 species with >7 individuals showed a positive association between cortisol and corticosterone among individuals, and repeated measures of the cortisol-to-corticosterone ratio within individuals were weakly associated (CV range 3-136%). We conclude that corticosterone, although at lower concentrations, has the potential to signal independently of cortisol, and should be included in integrated endocrine models of stress responses. (C) 2012 Elsevier Inc. All rights reserved.


Glucocorticoids; LC-MS/MS; Mammals; Serum; SPE; Stress

Published in

General and Comparative Endocrinology
2012, Volume: 177, number: 1, pages: 113-119

    UKÄ Subject classification

    Endocrinology and Diabetes
    Other Veterinary Science

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