TY - JOUR
T1 - Effects of corticosterone pellets on baseline and stress-induced corticosterone and corticosteroid-binding-globulin
AU - Müller, Claudia
AU - Almasi, Bettina
AU - Roulin, Alexandre
AU - Breuner, Creagh W.
AU - Jenni-Eiermann, Susanne
AU - Jenni, Lukas
N1 - Funding Information:
We thank Ueli Schaffner, Renate Wullschleger, Martin Fischer, Martin Gassner, Linda Bischoff, Christophe Bonetti, Annette Sauter, Jodok Guntern, Matthias Ernst, Lena Senn, Andreas Rieser, Sonja Braaker, Annick Morgenthaler, Ester Pellegrini, Juliette Jullierat, Silvan Rüttimann, Pascal König, Martin Amrein, Silvain Antoniazza, Deborah Ramseier, Silvan Bissegger and Kim Stier for their help in the field. Marc Kéry gave valuable statistical advice. Financial support for this study was provided by the Swiss National Science Foundation Grant 3100A0-104134 to L.J and S.J-E and PPOOAO-102913 to A.R.
PY - 2009/1/1
Y1 - 2009/1/1
N2 - Exogenous administration of glucocorticoids is a widely used and efficient tool to investigate the effects of elevated concentrations of these hormones in field studies. Because the effects of corticosterone are dose and duration-dependent, the exact course of plasma corticosterone levels after exogenous administration needs to be known. We tested the performance of self-degradable corticosterone pellets (implanted under the skin) in elevating plasma corticosterone levels. We monitored baseline (sampled within 3 min after capture) total corticosterone levels and investigated potential interactions with corticosteroid-binding-globulin (CBG) capacity and the endogenous corticosterone response to handling in Eurasian kestrel Falco tinnunculus and barn owl Tyto alba nestlings. Corticosterone pellets designed for a 7-day-release in rodents elevated circulating baseline total corticosterone during only 2-3 days compared to placebo-nestlings. Highest levels occurred 1-2 days after implantation and levels decreased strongly thereafter. CBG capacity was also increased, resulting in a smaller, but still significant, increase in baseline free corticosterone levels. The release of endogenous corticosterone as a response to handling was strong in placebo-nestlings, but absent 2 and 8 days after corticosterone pellet implantation. This indicates a potential shut-down of the hypothalamo-pituitary-adrenal axis after the 2-3 days of elevated baseline corticosterone levels. 20 days after pellet implantation, the endogenous corticosterone response to handling of nestlings implanted with corticosterone pellets attained similar levels as in placebo-nestlings. Self-degradable pellets proved to be an efficient tool to artificially elevate circulating baseline corticosterone especially in field studies, requiring only one intervention. The resulting peak-like elevation of circulating corticosterone, the concomitant elevation of CBG capacity, and the absence of an endogenous corticosterone response to an acute stressor have to be taken into account.
AB - Exogenous administration of glucocorticoids is a widely used and efficient tool to investigate the effects of elevated concentrations of these hormones in field studies. Because the effects of corticosterone are dose and duration-dependent, the exact course of plasma corticosterone levels after exogenous administration needs to be known. We tested the performance of self-degradable corticosterone pellets (implanted under the skin) in elevating plasma corticosterone levels. We monitored baseline (sampled within 3 min after capture) total corticosterone levels and investigated potential interactions with corticosteroid-binding-globulin (CBG) capacity and the endogenous corticosterone response to handling in Eurasian kestrel Falco tinnunculus and barn owl Tyto alba nestlings. Corticosterone pellets designed for a 7-day-release in rodents elevated circulating baseline total corticosterone during only 2-3 days compared to placebo-nestlings. Highest levels occurred 1-2 days after implantation and levels decreased strongly thereafter. CBG capacity was also increased, resulting in a smaller, but still significant, increase in baseline free corticosterone levels. The release of endogenous corticosterone as a response to handling was strong in placebo-nestlings, but absent 2 and 8 days after corticosterone pellet implantation. This indicates a potential shut-down of the hypothalamo-pituitary-adrenal axis after the 2-3 days of elevated baseline corticosterone levels. 20 days after pellet implantation, the endogenous corticosterone response to handling of nestlings implanted with corticosterone pellets attained similar levels as in placebo-nestlings. Self-degradable pellets proved to be an efficient tool to artificially elevate circulating baseline corticosterone especially in field studies, requiring only one intervention. The resulting peak-like elevation of circulating corticosterone, the concomitant elevation of CBG capacity, and the absence of an endogenous corticosterone response to an acute stressor have to be taken into account.
KW - Acute stress response
KW - Aves
KW - Corticosteroid-binding-globulin
KW - Corticosterone administration
KW - Falco tinnunculus
KW - Negative feedback regulation
KW - Post-natal
KW - Self-degrading implants
KW - Tyto alba
UR - http://www.scopus.com/inward/record.url?scp=57649230775&partnerID=8YFLogxK
U2 - 10.1016/j.ygcen.2008.10.018
DO - 10.1016/j.ygcen.2008.10.018
M3 - Article
C2 - 18996387
AN - SCOPUS:57649230775
SN - 0016-6480
VL - 160
SP - 59
EP - 66
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 1
ER -