Testosterone Mediates Seasonal Growth of the Song Control Nuclei in a Tropical Bird

Brain, Behavior and Evolution
Thomas W SmallIgnacio T Moore

Abstract

In mid- to high-latitude songbirds, seasonal reproduction is stimulated by increasing day length accompanied by elevated plasma sex steroid levels, increased singing, and growth of the song control nuclei (SCN). Plasticity of the SCN and song behavior are primarily mediated by testosterone (T) and its metabolites in most species studied thus far. However, the majority of bird species are tropical and have less pronounced seasonal reproductive cycles. We have previously documented that equatorial rufous-collared sparrows (Zonotrichia capensis) exhibit seasonal neuroplasticity in the SCN. Manipulating T in these birds, however, did not alter singing behavior. In the current study, we investigated whether T mediates plasticity of the SCN in a similar manner to temperate songbirds. In the first experiment, we treated captive male birds with T or blank implants during the nonbreeding season. In a second experiment, we treated captive male birds with either blank implants, T-filled implants, T with flutamide (FLU; an androgen receptor antagonist) or T with FLU and 1,4,6-androstatriene-3,17-dione (ATD; an estrogen synthesis inhibitor) during the breeding season. In both experiments, the volumes of the brain areas high vocal center (HV...Continue Reading

Citations

Apr 21, 2019·Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution·Jamily LorenaPatricia N Schneider
Jun 18, 2018·Hormones and Behavior·Olesya T ShevchoukJacques Balthazart
Nov 6, 2021·Human Nature : an Interdisciplinary Biosocial Perspective·Melvin Konner

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