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Scales tell a story on the stress history of fish.

Aerts J, Metz JR, Ampe B, Decostere A, Flik G, De Saeger S - PLoS ONE (2015)

Bottom Line: An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish.Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress.We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

View Article: PubMed Central - PubMed

Affiliation: Bio-analysis Research Group, Animal Sciences Unit, Institute for Agriculture and Fisheries Research, Melle, Belgium; Laboratory of Food Analysis, Department of Bio-analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.

ABSTRACT
Fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal (HPI-) axis to release cortisol into the blood. Scientifically validated biomarkers to capture systemic cortisol exposure over longer periods of time are of utmost importance to assess chronic stress in governmental, wildlife, aquaculture and scientific settings. Here we demonstrate that cortisol in scales of common carp (Cyprinus carpio L.) is the long-sought biomarker for chronic stress. Undisturbed (CTR) and daily stressed (STRESS) carp were compared. Dexamethasone (DEX) or cortisol (CORT) fed fish served as negative and positive controls, respectively. Scale cortisol was quantified with a validated ultra-performance liquid chromatography tandem mass spectrometry method. An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish. Scale cortisol content reflects its accumulation in a stressor and time dependent manner and validates the scale cortisol content as biomarker for chronic stress. Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress. The expression of HPI key genes crf, pomc, and star were up-regulated in STRESS fish in the absence of a plasma cortisol response, as was the target gene of cortisol encoding subunit α1 of the Na+/K+-ATPase in gills. When lost, scales of fish regenerate fast. Regenerated scales corroborate our findings, offering (i) unsurpassed time resolution for cortisol incorporation and as such for stressful events, and (ii) the possibility to investigate stress in a well defined and controlled environment and time frame creating novel opportunities for bone physiological research. We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

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Cortisol (pmol per scale) in ontogenetic scales after 21 and 42 days of treatment (CCα = decision limit and CCβ = detection capability were calculated using an average weight of 0.026 g per scale).One value (2.8 pmol per scale) of STRESS day 42 was omitted in the scatter/boxplot for reasons of presentation. Error bars in scatter/boxplots are defined as in Fig 1. For statistics, see S2 Table.
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pone.0123411.g004: Cortisol (pmol per scale) in ontogenetic scales after 21 and 42 days of treatment (CCα = decision limit and CCβ = detection capability were calculated using an average weight of 0.026 g per scale).One value (2.8 pmol per scale) of STRESS day 42 was omitted in the scatter/boxplot for reasons of presentation. Error bars in scatter/boxplots are defined as in Fig 1. For statistics, see S2 Table.

Mentions: All CTR and DEX fish showed scale cortisol values below the detection capability (CCβ), while most STRESS and CORT fish showed scale cortisol values above CCβ at both days (Fig 4).


Scales tell a story on the stress history of fish.

Aerts J, Metz JR, Ampe B, Decostere A, Flik G, De Saeger S - PLoS ONE (2015)

Cortisol (pmol per scale) in ontogenetic scales after 21 and 42 days of treatment (CCα = decision limit and CCβ = detection capability were calculated using an average weight of 0.026 g per scale).One value (2.8 pmol per scale) of STRESS day 42 was omitted in the scatter/boxplot for reasons of presentation. Error bars in scatter/boxplots are defined as in Fig 1. For statistics, see S2 Table.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414496&req=5

pone.0123411.g004: Cortisol (pmol per scale) in ontogenetic scales after 21 and 42 days of treatment (CCα = decision limit and CCβ = detection capability were calculated using an average weight of 0.026 g per scale).One value (2.8 pmol per scale) of STRESS day 42 was omitted in the scatter/boxplot for reasons of presentation. Error bars in scatter/boxplots are defined as in Fig 1. For statistics, see S2 Table.
Mentions: All CTR and DEX fish showed scale cortisol values below the detection capability (CCβ), while most STRESS and CORT fish showed scale cortisol values above CCβ at both days (Fig 4).

Bottom Line: An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish.Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress.We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

View Article: PubMed Central - PubMed

Affiliation: Bio-analysis Research Group, Animal Sciences Unit, Institute for Agriculture and Fisheries Research, Melle, Belgium; Laboratory of Food Analysis, Department of Bio-analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.

ABSTRACT
Fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal (HPI-) axis to release cortisol into the blood. Scientifically validated biomarkers to capture systemic cortisol exposure over longer periods of time are of utmost importance to assess chronic stress in governmental, wildlife, aquaculture and scientific settings. Here we demonstrate that cortisol in scales of common carp (Cyprinus carpio L.) is the long-sought biomarker for chronic stress. Undisturbed (CTR) and daily stressed (STRESS) carp were compared. Dexamethasone (DEX) or cortisol (CORT) fed fish served as negative and positive controls, respectively. Scale cortisol was quantified with a validated ultra-performance liquid chromatography tandem mass spectrometry method. An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish. Scale cortisol content reflects its accumulation in a stressor and time dependent manner and validates the scale cortisol content as biomarker for chronic stress. Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress. The expression of HPI key genes crf, pomc, and star were up-regulated in STRESS fish in the absence of a plasma cortisol response, as was the target gene of cortisol encoding subunit α1 of the Na+/K+-ATPase in gills. When lost, scales of fish regenerate fast. Regenerated scales corroborate our findings, offering (i) unsurpassed time resolution for cortisol incorporation and as such for stressful events, and (ii) the possibility to investigate stress in a well defined and controlled environment and time frame creating novel opportunities for bone physiological research. We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

Show MeSH
Related in: MedlinePlus