Meeting Abstract
P2.144 Wednesday, Jan. 5 Stress affects song control nuclei growth in adult male House Finches, Carpodacus mexicanus JAMES, KO*; RISO, GL; FRENCH, SS; STRAND, CR; Cal Poly St Univ, San Luis Obispo; Cal Poly St Univ, San Luis Obispo; Utah St Univ, Logan; Cal Poly St Univ, San Luis Obispo koj29@hotmail.com
Song production in songbirds is controlled by parts of the brain known as the song control nuclei (SCN). During spring, gonads increase in size, males sing to attract mates and SCN become larger. This neuroplasticity is controlled by the change in day length and increased plasma testosterone (T) levels. Plasma T can be reduced by stress through the production of corticosterone (B). To test whether stress/B affect neuroplasticity in SCN, we captured male house finches during winter and allowed them to acclimatize for one month on short days (8L:16D). We transferred birds to long days (16L:8D) to induce growth of the gonads, increase plasma T levels, and induce growth of SCN. We used a 30-minute restraint stress protocol on half of the birds two times a day for one week. We collected blood samples from birds on the first and last day to measure plasma T and B via radioimmunoassay. We then sacrificed the finches and processed the brains for immunohistochemistry. One series of sections was immunostained for NeuN to measure SCN volumes. We predicted that stressed birds would have higher B and lower T plasma concentrations than non-stressed birds and that growth of two SCN (HVC and RA) of stressed birds would be hindered. HVC volumes were smaller in stressed than non-stressed birds, while RA volumes did not differ. HVC volumes may have been smaller in stressed birds because of an inhibition of neurogenesis in this region. While restraint stress is an artificial stressor, it can provide important information regarding how chronic stress influences neuroplasticity and possibly decreases singing behavior and reproductive success in birds. Future work will address how natural stressors may affect neuroplasticity in birds.
