Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis)

M. B. Swett; C. W. Breuner

doi:10.1016/j.cbpa.2008.06.031

Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis)

M. B. Swett, C. W. Breuner

Division of Biological and Biomedical Sciences

University of Montana

Research output: Contribution to journal › Article › peer-review

31 Scopus citations

Abstract

Plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. Mammals have both sex steroid binding globulin (SSBG) and corticosteroid binding globulin (CBG). Birds, however, have no detectable SSBG, leading to the early conclusion that birds have no plasma regulation of sex steroids. CBG, however, can bind androgens with relatively high affinity. In birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology because glucocorticoids compete with androgens for CBG binding sites. We report levels of total testosterone (T), total corticosterone, CBG, and estimated free T in the males, the more aggressive morph had higher levels of total T; female morphs did not differ. Approximately 96% of T was bound to CBG, but a lack of morph or sex-specific differences in corticosterone titers or CBG capacity caused patterns of free T to mirror those of total T. While CBG has the potential to greatly influence T availability to tissues, in this species interactions between T, CBG and corticosterone do not appear to alter general patterns of T availability to tissues.

Original language	English
Pages (from-to)	226-231
Number of pages	6
Journal	Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume	151
Issue number	2
DOIs	https://doi.org/10.1016/j.cbpa.2008.06.031
State	Published - Oct 2008

Funding

We thank Glennis Julian and Haruka Wada for assistance with the assays. Samantha Burrell and Ruby Dale-Brown provided able assistance in the field. We are indebted to the Northwoods Stewardship Center, The Center for Environmental Research at Hornsby Bend and The Brackenridge Field Laboratory at the University of Texas for allowing us access to field sites. M. Swett is especially grateful to the staff of the Northwoods Stewardship Center and the Stevens Family for support in VT. This work was funded by a NSF Graduate Research Fellowship to MBS, graduate fellowship support from the Ecology, Evolution and Behavior Graduate Program at the University of Texas at Austin, and NSF IBN-0236536 to CWB.

Funders	Funder number
University of Texas at Austin	IBN-0236536

Keywords

Behavioral polymorphism
Corticosterone
Corticosterone binding globulin
Free-hormone hypothesis
Testosterone
White-throated sparrow

Access to Document

10.1016/j.cbpa.2008.06.031

Cite this

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title = "Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis)",

abstract = "Plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. Mammals have both sex steroid binding globulin (SSBG) and corticosteroid binding globulin (CBG). Birds, however, have no detectable SSBG, leading to the early conclusion that birds have no plasma regulation of sex steroids. CBG, however, can bind androgens with relatively high affinity. In birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology because glucocorticoids compete with androgens for CBG binding sites. We report levels of total testosterone (T), total corticosterone, CBG, and estimated free T in the males, the more aggressive morph had higher levels of total T; female morphs did not differ. Approximately 96\% of T was bound to CBG, but a lack of morph or sex-specific differences in corticosterone titers or CBG capacity caused patterns of free T to mirror those of total T. While CBG has the potential to greatly influence T availability to tissues, in this species interactions between T, CBG and corticosterone do not appear to alter general patterns of T availability to tissues.",

keywords = "Behavioral polymorphism, Corticosterone, Corticosterone binding globulin, Free-hormone hypothesis, Testosterone, White-throated sparrow",

author = "Swett, \{M. B.\} and Breuner, \{C. W.\}",

note = "Funding Information: We thank Glennis Julian and Haruka Wada for assistance with the assays. Samantha Burrell and Ruby Dale-Brown provided able assistance in the field. We are indebted to the Northwoods Stewardship Center, The Center for Environmental Research at Hornsby Bend and The Brackenridge Field Laboratory at the University of Texas for allowing us access to field sites. M. Swett is especially grateful to the staff of the Northwoods Stewardship Center and the Stevens Family for support in VT. This work was funded by a NSF Graduate Research Fellowship to MBS, graduate fellowship support from the Ecology, Evolution and Behavior Graduate Program at the University of Texas at Austin, and NSF IBN-0236536 to CWB. ",

year = "2008",

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AU - Breuner, C. W.

N1 - Funding Information: We thank Glennis Julian and Haruka Wada for assistance with the assays. Samantha Burrell and Ruby Dale-Brown provided able assistance in the field. We are indebted to the Northwoods Stewardship Center, The Center for Environmental Research at Hornsby Bend and The Brackenridge Field Laboratory at the University of Texas for allowing us access to field sites. M. Swett is especially grateful to the staff of the Northwoods Stewardship Center and the Stevens Family for support in VT. This work was funded by a NSF Graduate Research Fellowship to MBS, graduate fellowship support from the Ecology, Evolution and Behavior Graduate Program at the University of Texas at Austin, and NSF IBN-0236536 to CWB.

PY - 2008/10

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N2 - Plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. Mammals have both sex steroid binding globulin (SSBG) and corticosteroid binding globulin (CBG). Birds, however, have no detectable SSBG, leading to the early conclusion that birds have no plasma regulation of sex steroids. CBG, however, can bind androgens with relatively high affinity. In birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology because glucocorticoids compete with androgens for CBG binding sites. We report levels of total testosterone (T), total corticosterone, CBG, and estimated free T in the males, the more aggressive morph had higher levels of total T; female morphs did not differ. Approximately 96% of T was bound to CBG, but a lack of morph or sex-specific differences in corticosterone titers or CBG capacity caused patterns of free T to mirror those of total T. While CBG has the potential to greatly influence T availability to tissues, in this species interactions between T, CBG and corticosterone do not appear to alter general patterns of T availability to tissues.

AB - Plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. Mammals have both sex steroid binding globulin (SSBG) and corticosteroid binding globulin (CBG). Birds, however, have no detectable SSBG, leading to the early conclusion that birds have no plasma regulation of sex steroids. CBG, however, can bind androgens with relatively high affinity. In birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology because glucocorticoids compete with androgens for CBG binding sites. We report levels of total testosterone (T), total corticosterone, CBG, and estimated free T in the males, the more aggressive morph had higher levels of total T; female morphs did not differ. Approximately 96% of T was bound to CBG, but a lack of morph or sex-specific differences in corticosterone titers or CBG capacity caused patterns of free T to mirror those of total T. While CBG has the potential to greatly influence T availability to tissues, in this species interactions between T, CBG and corticosterone do not appear to alter general patterns of T availability to tissues.

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KW - Free-hormone hypothesis

KW - Testosterone

KW - White-throated sparrow

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Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis)

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