title: Dynamic interactions between corticosterone, corticosteroid binding globulin and testosterone in response to capture stress in male breeding Eurasian tree sparrows.
abstract: In birds, corticosterone (CORT), testosterone (T), and corticosteroid binding globulin (CBG) are involved in modulating the trade-off between reproduction and survival. In response to acute stress, increased total plasma CORT is a ubiquitous phenomenon while T levels can decrease, or remain unchanged. Since CORT and T bind competitively with CBG in birds, the underlying regulatory mechanisms and consequences of their dynamic interactions remain largely unknown. Here, we studied the dynamic changes of total CORT, T, and CBG, and estimated free and bound CORT and T in response to capture stress in male Eurasian tree sparrows (Passer montanus) across the nest building, egg-laying, and nestling stages. We predicted that free, bound and total hormone concentrations would increase for CORT and decrease for T in response to acute stress, and the relative magnitude of these changes would vary with life history stage. We found that baseline and stressed-induced CORT values did not vary across breeding sub-stages. However, total and bound CORT increased with stress while free remained unchanged. Baseline levels of total, free and bound T were highest during the nest building and it was the only stage in which all measures of T were affected by stress. Regardless of breeding stage or restraint stress, we did not detect a significant correlation between CORT and T. CBG was found to be mostly unoccupied by steroid hormones under stress and stress-free conditions and this likely provided an adequate buffer for changes in free levels of CORT and T during unpredictable environmental perturbations.
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
authors.forename: Yaqing
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China; Ocean College of Hebei Agricultural University, Qinhuangdao 066003, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, USA.
authors.forename: Jesse S
authors.initials: JS
authors.lastname: Krause
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
authors.forename: Mo
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
authors.forename: Xuelu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China. Electronic address: wuyuefeng@hebtu.edu.cn.
authors.forename: Yuefeng
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China; Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, USA. Electronic address: lidngmng@gmail.com.
authors.forename: Dongming
authors.initials: D
authors.lastname: Li
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000097:blood*; D001947:Breeding; D002681:China; D003345:Corticosterone / Q000097:blood*; D008297:Male; D046370:Sparrows / Q000097:blood* / Q000502:physiology*; D013312:Stress, Physiological; D013739:Testosterone / Q000097:blood*; D014156:Transcortin / Q000378:metabolism*
chemical_list: D030161:Avian Proteins; D013739:Testosterone; D014156:Transcortin; D003345:Corticosterone
keywords: Corticosteroid binding globulin; Corticosterone; Eurasian tree sparrow; Reproduction; Testosterone