Estrogen contributes to seasonal plasticity of the adult avian song control system.

Full Abstract

Songbirds show dramatic neural plasticity as adults, including large-scale anatomical changes in discrete brain regions ("song control nuclei") controlling the production of singing behavior. The volumes of several song control nuclei are much larger in the breeding season than in the nonbreeding season, and these seasonal neural changes are regulated by plasma testosterone (T) levels. In many cases, the effects of T on the central nervous system are mediated by neural conversion to estradiol (E(2)) by the enzyme aromatase. The forebrain of male songbirds expresses very high levels of aromatase, in some cases adjacent to song control nuclei. We examined the effects of aromatase inhibition and estrogen treatment on song nuclei size using wild male songbirds in both the breeding and nonbreeding seasons. In breeding males, aromatase inhibition caused the volume of a telencephalic song control nucleus (HVC) to decrease, and this effect was partially rescued by concurrent estrogen replacement. In nonbreeding males, estradiol treatment caused HVC to grow to maximal spring size within 2 weeks. Overall, these data suggest that aromatization of T is an important mediator of song control system plasticity, and that estradiol has neurotrophic effects in adult male songbirds. This study demonstrates that estrogen can affect adult neural plasticity on a gross anatomical scale and is the first examination of estrogen effects on the brain of a wild animal. Copyright 2003 Wiley Periodicals, Inc. J Neurobiol 58: 413-422, 2004

Author information

Author/s: Soma, Kiran K (KK); Tramontin, Anthony D (AD); Featherstone, Joy (J); Brenowitz, Eliot A (EA);

Affiliation: Department of Physiological Science, University of California, Los Angeles, California 90095-1527, USA. kiran(-atsign-)physci.ucla.edu

Grants: MH53032 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.

Journal: Journal of neurobiology (J Neurobiol), published in United States. (Language: eng)

Reference: 2004-Feb; vol 58 (issue 3) : pp 413-22

Dates: Created 2004/01/29; Completed 2004/05/03; Revised 2007/11/14;

PMID: 14750153, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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