Melatonin and corticosterone profiles under polar day in a seabird with sexually opposite activity-rhythms

Huffeldt, N. P., Mekel, F. R., Jenni-Eiermann, S., Goymann, W. and Helm, B. (2020) Melatonin and corticosterone profiles under polar day in a seabird with sexually opposite activity-rhythms. General and Comparative Endocrinology, 285, 113296. (doi: 10.1016/j.ygcen.2019.113296) (PMID:31589833)

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Abstract

The 24 h geophysical light-dark cycle is the main organizer of daily rhythms, scheduling physiology and behavior. This cycle attenuates greatly during the continuous light of summer at polar latitudes, resulting in species-specific and even individual-specific patterns of behavioral rhythmicity, but the physiological mechanisms underlying this variation are poorly understood. To address this knowledge gap and to better understand the roles of the hormones melatonin and corticosterone in rhythmic behavior during this ‘polar day’, we exploited the behavior of thick-billed murres (Uria lomvia), a charadriiform seabird with sexually opposite (‘antiphase’) activity-rhythms that have a duration of 24 h. Melatonin concentration in the plasma of inactive males was unexpectedly high around midday and subsequently fell during a sudden decrease in light intensity as the colony became shaded. Corticosterone concentration in plasma did not vary with time of day or activity in either sex. While the reasons for these unusual patterns remain unclear, we propose that a flexible melatonin response and little diel variation of corticosterone may be adaptive in thick-billed murres, and perhaps other polar birds and mammals, by stabilizing glucocorticoids’ role of modulating energy storage and mobilization across the diel cycle and facilitating the appropriate reaction to unexpected stimuli experienced across the diel cycle while attending the colony.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Helm, Dr Barbara
Authors: Huffeldt, N. P., Mekel, F. R., Jenni-Eiermann, S., Goymann, W., and Helm, B.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:General and Comparative Endocrinology
Publisher:Elsevier
ISSN:0016-6480
ISSN (Online):1095-6840
Published Online:04 October 2019
Copyright Holders:Copyright © 2019 Elsevier Inc.
First Published:First published in General and Comparative Endocrinology 285:113296
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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