Meeting Abstract
P3.117 Wednesday, Jan. 6 The role of glucocorticoid receptors and stress on the development of the avian song system SHAHBAZI*, M.**; CARRUTH, L.L.; Neuroscience Inst., Georgia State Univ.; Neuroscience Inst., Georgia State Univ. biomxs@langate.gsu.edu
When male zebra finches (Taeniopygia guttata) experience early developmental stress they exhibit reduced song complexity and a decreased HVC size in adulthood. Song nucleus HVC is required for learning and production of song and song complexity is important for mate choice. This reduction in song complexity and song nucleus size suggests a direct link between the stress response, brain and behavior, however the mechanisms underlying these effects are unknown. We are investigating the role of glucocorticoid receptors and stress on the development of the avian song system. Glucocorticoid receptor-like immunoreactive-neurons (GR-like ir-neurons) were localized in the brains of male zebra finches collected on P1 (post-hatch day 1, song nuclei not yet formed), P10 (post-hatch day 10, song nuclei formed), and adult birds (post-hatch day 90 or older, sexually mature and singing crystallized songs). In adults, high density of glucocorticoid receptor-like immunoreactivity was found in the HVC, tubero-infundibular area, nucleus paraventricularis (PVN), posteromedialis and lateralis hypothalami, nucleus septi lateralis, tectum opticum, and brainstem nuclei including the locus coeruleus and raphe nucleus. The cerebellar cortex and hippocampal formation were also immunopositive. In addition, adult birds that were stressed from P5-26, via chronic corticosterone treatments, had significantly smaller HVC volumes and altered regulation of GR-like ir-neurons in several telencephalic and diencephalic brain regions when measured in adulthood. Plasma corticosterone concentrations were measured using radioimmunoassay to validate the treatments and compare treated versus control birds. The mechanism of how chronic stress influences HVC size is yet to be determined.
