HORMONE-INDUCED ADULT NEUROPLASTICITY AND THE ACTIVATION OF BEHAVIOR IN BIRDS
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1
Johns Hopkins University, Department of Psychological & Brain Sciences, United States
Steroid hormones bind to their cognate receptors and act as transcription factors in the brain to facilitate changes in behavior. These hormonal effects on behavior are often associated marked changes in the brain, even in adult animals. I will review in this presentation work on steroid-dependent plasticity in birds based on two cases: the medial preoptic nucleus (POM) of Japanese quail in relation to the control of male sexual behavior and the song nucleus HVC in canaries that regulates aspects of song behavior. In male quail, POM volume changes in volume seasonally (larger under breeding conditions than non-breeding conditions. In castrated subjects testosterone can almost double POM volume within two weeks. Significant volume increases are, however, already observable after one day of treatment. The Steroid Receptor Coactivator-1 is part of the mechanism mediating these effects. Increases in POM volume reflect changes in cell size or spacing and dendritic branching but are not associated with an increase in neuron number. In contrast, seasonal changes in HVC volume reflect incorporation of newborn neurons in addition to changes in cell size and spacing in neurons and glia. HVC volume is larger when birds are sampled in pre-breeding or breeding conditions than in those who are not breeding. These types of changes can be induced by treatments with exogenous testosterone or its estrogenic and androgenic metabolites. Expression of doublecortin, a microtubule-associated protein that is a marker of new neurons, is increased by testosterone in HVC but not in the adjacent nidopallium suggesting that neuron production in the subventricular zone, the birthplace of newborn neurons, is not affected. Testosterone acting through both androgenic and estrogenic metabolites promotes the recruitment of new neurons to HVC. Together these data illustrate that hormone effects on behavior can be mediated by distinct action of steroids at the cellular level.
Acknowledgements
Acknowledgements: Thanks to NIH/NINDS R01 NS35467 and NIH/NIMH R01 MH50388 for support.
Keywords:
adult neurogenesis,
doublecortin,
Preoptic Area,
SEASONAL PLASTICITY,
Songbirds,
Testosterone
Conference:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011.
Presentation Type:
Invited Symposium
Topic:
Brain and behavior
Citation:
Ball
GF
(2011). HORMONE-INDUCED ADULT NEUROPLASTICITY AND THE ACTIVATION OF BEHAVIOR IN BIRDS.
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00107
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Received:
03 Aug 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Prof. Gregory F Ball, Johns Hopkins University, Department of Psychological & Brain Sciences, Baltimore, MD, 21218, United States, gball@jhu.edu