Serum corticosteroid binding globulin expression is modulated by fasting in polar bears (Ursus maritimus)

Chow, Brian A.; Hamilton, Jason; Cattet, Marc; Stenhouse, Gordon B.; Obbard, Martyn E.; Vijayan, Mathilakath M.

doi:10.1016/j.cbpa.2010.09.017

Cited by 18 publications

(22 citation statements)

References 41 publications

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“…In the present study, however, with a five-fold sample size, hair cortisol seems to be neither sex nor age dependent. This is in accordance with the hair studies by Bennet & Hayssen (2010; domestic dog) and Macbeth et al (2010; grizzly bear), whereas studies on cortisol in other matrices in different species seemed more inconclusive in this regard (Handa et al1994; Dobson and Smith 2000; Tryland et al 2002; Oskam et al 2004; Chow et al 2010, 2011). …”

Section: Discussionsupporting

confidence: 86%

Measuring environmental stress in East Greenland polar bears, 1892–1927 and 1988–2009: What does hair cortisol tell us?

Bechshøft

Rigét

Sonne

et al. 2012

Environment International

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Hair sampled from 96 East Greenland polar bears (Ursus maritimus) over the periods 1892–1927 and 1988–2009 was analyzed for cortisol as a proxy to investigate temporal patterns of environmental stress. Cortisol concentration was independent of sex and age, and was found at significantly higher (p < 0.001) concentrations in historical hair samples (1892–1927; n = 8) relative to recent ones (1988–2009; n = 88). In addition, there was a linear time trend in cortisol concentration of the recent samples (p < 0.01), with an annual decrease of 2.7 %. The recent hair samples were also analyzed for major bioaccumulative, persistent organic pollutants (POPs). There were no obvious POP related time trends or correlations between hair cortisol and hair POP concentrations. Thus, polar bear hair appears to be a relatively poor indicator of the animal’s general POP load in adipose tissue. However, further investigations are warranted to explore the reasons for the temporal decrease found in the bears’ hair cortisol levels.

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Section: Discussionsupporting

confidence: 86%

Measuring environmental stress in East Greenland polar bears, 1892–1927 and 1988–2009: What does hair cortisol tell us?

Bechshøft

Rigét

Sonne

et al. 2012

Environment International

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“…Tryland et al (2002) however, found no difference in cortisol levels related to sex, which corresponds to our results when the outlier was not removed. Similarly, Chow et al (2010a,b) found no sex differences in either polar bear or grizzly bear serum total cortisol concentration, whereas serum CBG (corticosteroid binding globulin) expression was significantly higher in adult females compared to males (grizzly bear) and significantly elevated in lactating females relative to males and solitary female bears (polar bear), respectively.…”

Section: Discussionmentioning

confidence: 89%

Cortisol levels in hair of East Greenland polar bears

Bechshøft

Sonne

Dietz

et al. 2011

Science of The Total Environment

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To demonstrate the ability to assess long-term hypothalamic-pituitary-adrenocortical (HPA) axis activity in polar bears (Ursus maritimus), a pilot study was conducted in which cortisol concentrations was analyzed in hair from 7 female (3-19 years) and 10 male (6-19 years) East Greenland polar bears sampled 1994-2006. Hair was chosen as matrix as it is non-invasive, seasonally harmonized, and has been validated as an index of long-term changes in cortisol levels. Samples were categorized according to contamination: Eight were clean (2 females, 6 males), 5 had been contaminated with bear blood (2 F, 3 M), and 4 with bear fat (3 F, 1 M). There was no significant difference in cortisol concentration between the three categories after external contamination was removed. However, contaminated hair samples should be cleaned before cortisol determination. Average hair cortisol concentration was 8.90 pg/mg (range: 5.5 to 16.4 pg/ mg). There was no significant correlation between cortisol concentration and age (p = 0.81) or sampling year (p = 0.11). However, females had higher mean cortisol concentration than males (females mean: 11.0 pg/mg, males: 7.3 pg/mg; p = 0.01). The study showed that polar bear hair contains measurable amounts of cortisol and that cortisol in hair may be used in studies of longterm stress in polar bears.

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“…In this investigation, cortisol was measured in hair collected in September or October, which should represent the majority of the hair growth period for the SH polar bear subpopulation and may reflect HPA activity associated with 1) the spring‐early summer foraging period (Obbard et al 2007), 2) the breeding season (Ramsay and Stirling 1986), 3) the onshore fast (Stirling and Parkinson 2006, Obbard et al 2007), and 4) lactation–offspring care (Arnould and Ramsay 1994). Differences in basal or seasonal HPA activity (Oskam et al 2004, Hamilton 2007, Chow et al 2011) along with divergent energetic demands, stressors, or response to stressors are well‐documented at different stages of the polar bear life cycle (Derocher et al 2004). Together, these factors may explain the patterns of HCC we recorded in SH polar bears (Landys et al 2006, Busch and Hayward 2009, Wingfield et al 2011).…”

Section: Discussionmentioning

confidence: 99%

“…These findings suggest that the presence or absence of dependent offspring may have a relatively strong influence on HCC levels in independent SH polar bears. Energy deficits are known to be associated with increased HPA activity (Busch and Hayward 2009), and the demands of lactation may be a key factor in this observation (Owen et al 2005, Chow et al 2011, Wingfield et al 2011). Lactation is known to be especially costly in polar bears, which fast during the first 2–3 months of lactation, produce milk with a high fat content, and rely solely on maternal fat reserves to support mother and offspring until they return to the sea‐ice to hunt (Arnould and Ramsay 1994).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of hair cortisol concentration as a biomarker of long‐term stress in free‐ranging polar bears

Macbeth¹,

Cattet²,

Obbard³

et al. 2012

Wildlife Society Bulletin

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Long-term physiological stress in individual animals may be an important mechanism linking ecological change with impaired wildlife population health. In the Southern Hudson Bay (SH) subpopulation of polar bears (Ursus maritimus), increasing stress associated with climate warming may be related to declining body condition. Accordingly, the development of tools to assess long-term stress in this species may prove invaluable for conservation efforts in this threatened population. The measurement of hair cortisol concentration (HCC) has shown promise as a potential biomarker of long-term stress in free-ranging bears. However, to serve as a useful management tool, factors influencing HCC in polar bears must be identified and then revealed to establish linkages between environmental conditions and the fitness of individual animals. We determined HCC (median ¼ 0.48 pg/mg [range ¼ 0.16-2.26 pg/mg]) in 185 polar bears captured in southern Hudson Bay from 2007 to 2009. HCC was influenced by sex, family group status, and capture period but not by body region or hair type. Using models developed through a combination of hypothesis testing and information theory, we also determined that HCC was negatively associated with growth indices (length, mass, and body condition index) linked to fitness in polar bears. Additional research will be required across several polar bear populations to establish the utility of HCC as a tool for polar bear conservation. ß 2012 The Wildlife Society.

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Serum corticosteroid binding globulin expression is modulated by fasting in polar bears (Ursus maritimus)

Cited by 18 publications

References 41 publications

Measuring environmental stress in East Greenland polar bears, 1892–1927 and 1988–2009: What does hair cortisol tell us?

Measuring environmental stress in East Greenland polar bears, 1892–1927 and 1988–2009: What does hair cortisol tell us?

Cortisol levels in hair of East Greenland polar bears

Evaluation of hair cortisol concentration as a biomarker of long‐term stress in free‐ranging polar bears

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