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Title: Dehydroepiandrosterone Heightens Aggression and Increases Androgen Receptor and Aromatase mRNA Expression in the Brain of a Male Songbird

Dehydroepiandrosterone (DHEA) is a testosterone/oestrogen precursor and known modulator of vertebrate aggression. Male song sparrows (Melospiza melodia morphna) show high aggression during breeding and nonbreeding life‐history stages when circulatingDHEAlevels are high, and low aggression during molt whenDHEAlevels are low. We previously showed that androgen receptor and aromatasemRNAexpression are higher during breeding and/or nonbreeding in brain regions associated with reproductive and aggressive behaviour, although the potential role ofDHEAin mediating these seasonal changes remained unclear. In the present study, nonbreeding male song sparrows were captured and held in the laboratory under short days (8 : 16 h light/dark cycle) and implanted with s.c.DHEA‐filled or empty (control) implants for 14 days.DHEAimplants increased aggression in a laboratory‐based simulated territorial intrusion. Brains ofDHEA‐implanted birds showed higher aromatasemRNAexpression in the preoptic area (POA) and higher androgen receptormRNAexpression in the periventricular nucleus of the medial striatum (pvMSt) and ventromedial nucleus of the hypothalamus. TheDHEA‐induced increases in aromatase expression in thePOAand androgen receptor expression in the pvMSt are consistent with previously reported seasonal increases in these markers associated with naturally elevatedDHEAlevels. This suggests thatDHEAfacilitates seasonal increases in aggression in nonbreeding male song sparrows by up‐regulating steroid signalling/synthesis machinery in a brain region‐specific fashion.

 
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PAR ID:
10197740
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Journal of Neuroendocrinology
Volume:
28
Issue:
12
ISSN:
0953-8194
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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