TY - JOUR
T1 - Sex steroid-induced neuroplasticity and behavioral activation in birds
AU - Balthazart, Jacques
AU - Charlier, Thierry D.
AU - Barker, Jennifer M.
AU - Yamamura, Takashi
AU - Ball, Gregory F.
PY - 2010/12
Y1 - 2010/12
N2 - The brain of adult homeothermic vertebrates exhibits a higher degree of morphological neuroplasticity than previously thought, and this plasticity is especially prominent in birds. In particular, incorporation of new neurons is widespread throughout the adult avian forebrain, and the volumes of specific nuclei vary seasonally in a prominent manner. We review here work on steroid-dependent plasticity in birds, based on two cases: the medial preoptic nucleus (POM) of Japanese quail in relation to male sexual behavior, and nucleus HVC in canaries, which regulates song behavior. In male quail, POM volume changes seasonally, and in castrated subjects testosterone almost doubles POM volume within 2 weeks. Significant volume increases are, however, already observable after 1 day. 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. These are induced by treatments with exogenous testosterone or its metabolites. Expression of doublecortin, a microtubule-associated protein, is increased by testosterone in the HVC but not in the adjacent nidopallium, suggesting that neuron production in the subventricular zone, the birthplace of newborn neurons, is not affected. Together, these data illustrate the high degree of plasticity that extends into adulthood and is characteristic of avian brain structures. Many questions still remain concerning the regulation and specific function of this plasticity.
AB - The brain of adult homeothermic vertebrates exhibits a higher degree of morphological neuroplasticity than previously thought, and this plasticity is especially prominent in birds. In particular, incorporation of new neurons is widespread throughout the adult avian forebrain, and the volumes of specific nuclei vary seasonally in a prominent manner. We review here work on steroid-dependent plasticity in birds, based on two cases: the medial preoptic nucleus (POM) of Japanese quail in relation to male sexual behavior, and nucleus HVC in canaries, which regulates song behavior. In male quail, POM volume changes seasonally, and in castrated subjects testosterone almost doubles POM volume within 2 weeks. Significant volume increases are, however, already observable after 1 day. 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. These are induced by treatments with exogenous testosterone or its metabolites. Expression of doublecortin, a microtubule-associated protein, is increased by testosterone in the HVC but not in the adjacent nidopallium, suggesting that neuron production in the subventricular zone, the birthplace of newborn neurons, is not affected. Together, these data illustrate the high degree of plasticity that extends into adulthood and is characteristic of avian brain structures. Many questions still remain concerning the regulation and specific function of this plasticity.
KW - Doublecortin
KW - HVC
KW - Japanese quail
KW - Preoptic area
KW - Sexual behavior
KW - Song control system
KW - Songbirds
UR - http://www.scopus.com/inward/record.url?scp=78650001648&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78650001648&partnerID=8YFLogxK
U2 - 10.1111/j.1460-9568.2010.07518.x
DO - 10.1111/j.1460-9568.2010.07518.x
M3 - Article
C2 - 21143666
AN - SCOPUS:78650001648
SN - 0953-816X
VL - 32
SP - 2116
EP - 2132
JO - European Journal of Neuroscience
JF - European Journal of Neuroscience
IS - 12
ER -