Regulation of free corticosterone and CBG capacity under different environmental conditions in altricial nestlings.

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State: Public
Version: Final published version
Serval ID
serval:BIB_3DE0F85EA8BD
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Regulation of free corticosterone and CBG capacity under different environmental conditions in altricial nestlings.
Journal
General and Comparative Endocrinology
Author(s)
Almasi B., Roulin A., Jenni-Eiermann S., Breuner C.W., Jenni L.
ISSN
1095-6840[electronic], 0016-6480[linking]
Publication state
Published
Issued date
2009
Peer-reviewed
Oui
Volume
164
Number
2-3
Pages
117-124
Language
english
Abstract
The concentration of circulating glucocorticoids is regulated in response to environmental and endogenous conditions. Total circulating corticosterone, the main glucocorticoid in birds, consists of a fraction which is bound to corticosterone-binding globulins (CBG) and a free fraction. There is increasing evidence that the environment modulates free corticosterone levels through varying the concentration of CBG, but experimental evidence is lacking. To test the hypothesis that the regulation of chronic stress in response to endogenous and environmental conditions involves variation in both corticosterone release and CBG capacity, we performed an experiment with barn owl (Tyto alba) nestlings in two different years with pronounced differences in environmental conditions and in nestlings experimentally fed ad libitum. In half of the individuals we implanted a corticosterone-releasing pellet to artificially increase corticosterone levels and in the other half we implanted a placebo pellet. We then repeatedly collected blood samples to measure the change in total and free corticosterone levels as well as CBG capacity. The increase in circulating total corticosterone after artificial corticosterone administration varied with environmental conditions and with the food regime of the nestlings. The highest total corticosterone levels were found in nestlings growing up in poor environmental conditions and the lowest in ad libitum fed nestlings. CBG was highest in the year with poor environmental conditions, so that, contrary to total corticosterone, free corticosterone levels were low under poor environmental conditions. When nestlings were fed ad libitum total corticosterone, CBG and free corticosterone did not increase when administering corticosterone. These results suggest that depending on the individual history an animal experienced during development the HPA-axis is regulated differently.
Keywords
Animals, Body Constitution/drug effects, Body Constitution/physiology, Cohort Studies, Corticosterone/administration & dosage, Corticosterone/blood, Drug Implants, Environment, Female, Hypothalamo-Hypophyseal System/drug effects, Hypothalamo-Hypophyseal System/physiology, Male, Metabolic Clearance Rate, Nesting Behavior/drug effects, Nesting Behavior/physiology, Pituitary-Adrenal System/drug effects, Pituitary-Adrenal System/physiology, Placebos, Population Density, Strigiformes/blood, Strigiformes/metabolism, Transcortin/analysis
Pubmed
Web of science
Create date
22/10/2009 16:38
Last modification date
20/08/2019 14:34
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