Advanced

Androgens and the immunocompetence handicap hypothesis: Unraveling direct and indirect pathways of immunosuppression in song sparrows

Owen-Ashley, N T; Hasselquist, Dennis LU and Wingfield, J C (2004) In American Naturalist 164(4). p.490-505
Abstract
The immunocompetence handicap hypothesis proposes that testosterone (T)-dependent sexual signals are honest indicators of male health or genetic quality because only high-quality males are able to withstand the obligate effects of T-induced immunosuppression. In birds, the basic assumption that T suppresses immune function is equivocal, and the physiological mechanisms underlying T-induced immunosuppression remain to be investigated. We explored the proximate pathways of T-induced immunosuppression in song sparrows (Melospiza melodia) by treating captive nonbreeding males with different androgens and measuring several components of acquired immune function. Males implanted with T suppressed cell-mediated and humoral immune responses... (More)
The immunocompetence handicap hypothesis proposes that testosterone (T)-dependent sexual signals are honest indicators of male health or genetic quality because only high-quality males are able to withstand the obligate effects of T-induced immunosuppression. In birds, the basic assumption that T suppresses immune function is equivocal, and the physiological mechanisms underlying T-induced immunosuppression remain to be investigated. We explored the proximate pathways of T-induced immunosuppression in song sparrows (Melospiza melodia) by treating captive nonbreeding males with different androgens and measuring several components of acquired immune function. Males implanted with T suppressed cell-mediated and humoral immune responses compared to males implanted with 5proportional to-dihydrotestosterone (DHT), dehydroepiandrosterone, or control ( empty) implants. Furthermore, T treatment increased plasma levels of corticosterone and decreased body mass and fat stores in relation to other treatments. The failure of DHT to depress immune function suggests that T-induced immunosuppression does not occur through a direct pathway because both T and DHT bind to androgen receptors on target cells. Instead, we outline indirect pathways that are likely responsible for suppression of the avian immune system that include stress-induced immunosuppression, aromatization to estrogen, and alterations in energy allocation that constrain expenditures toward immune system activation. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
immunosuppression, song sparrow, testosterone, corticosterone, androgens, immunocompetence
in
American Naturalist
volume
164
issue
4
pages
490 - 505
publisher
University of Chicago Press
external identifiers
  • wos:000224079900008
  • scopus:6344265162
ISSN
0003-0147
language
English
LU publication?
yes
id
35d99101-0856-4dcb-94ff-2401f544c41c (old id 136894)
alternative location
http://proquest.umi.com/pqdlink?index=4&did=729955661&SrchMode=2&sid=6&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209455076&clientId=53681
date added to LUP
2007-06-25 13:41:46
date last changed
2017-06-25 03:37:07
@article{35d99101-0856-4dcb-94ff-2401f544c41c,
  abstract     = {The immunocompetence handicap hypothesis proposes that testosterone (T)-dependent sexual signals are honest indicators of male health or genetic quality because only high-quality males are able to withstand the obligate effects of T-induced immunosuppression. In birds, the basic assumption that T suppresses immune function is equivocal, and the physiological mechanisms underlying T-induced immunosuppression remain to be investigated. We explored the proximate pathways of T-induced immunosuppression in song sparrows (Melospiza melodia) by treating captive nonbreeding males with different androgens and measuring several components of acquired immune function. Males implanted with T suppressed cell-mediated and humoral immune responses compared to males implanted with 5proportional to-dihydrotestosterone (DHT), dehydroepiandrosterone, or control ( empty) implants. Furthermore, T treatment increased plasma levels of corticosterone and decreased body mass and fat stores in relation to other treatments. The failure of DHT to depress immune function suggests that T-induced immunosuppression does not occur through a direct pathway because both T and DHT bind to androgen receptors on target cells. Instead, we outline indirect pathways that are likely responsible for suppression of the avian immune system that include stress-induced immunosuppression, aromatization to estrogen, and alterations in energy allocation that constrain expenditures toward immune system activation.},
  author       = {Owen-Ashley, N T and Hasselquist, Dennis and Wingfield, J C},
  issn         = {0003-0147},
  keyword      = {immunosuppression,song sparrow,testosterone,corticosterone,androgens,immunocompetence},
  language     = {eng},
  number       = {4},
  pages        = {490--505},
  publisher    = {University of Chicago Press},
  series       = {American Naturalist},
  title        = {Androgens and the immunocompetence handicap hypothesis: Unraveling direct and indirect pathways of immunosuppression in song sparrows},
  volume       = {164},
  year         = {2004},
}