Meeting Abstract
89.1 Monday, Jan. 6 13:30 Acute and persistent social challenges elicit widespread shifts in peripheral gene expression without a systemic rise in testosterone ROSVALL, KA*; PETERSON, MP; BUECHLEIN, A; TANG, H; RUSCH, D; KETTERSON, ED; Indiana Univ.; Indiana Univ.; Indiana Univ.; Indiana Univ.; Indiana Univ.; Indiana Univ. krosvall@indiana.edu
The challenge hypothesis predicts that testosterone (T) rises following a social challenge to bring about changes in behavior and physiology that prepare animals for continued social instability. Evidence has been accumulating, however, that males of many songbird species do not socially modulate T, raising key questions about the nature of alternative physiological mechanisms related to social instability. We staged social challenges in free-living male dark-eyed juncos (Junco hyemalis), a species of songbird that under most circumstances does not elevate T in response to a simulated territorial intrusion. We hypothesized that tissue-specific changes in gene expression might prime individuals for continued social competition, at the expense of self-maintenance, even in the absence of a systemic rise in T. We used custom microarrays to assess these transcriptional responses in the liver, spleen, and pectoral muscle in males that were euthanized immediately after one 25-min playback (acute challenge), males that were euthanized on the day after a full day of repeated playbacks (persistent challenge), and unmanipulated controls. Both acute and persistent challenges led to many significant changes in gene expression in these three peripheral tissues, but T and corticosterone levels were unaffected. Consistent with our hypothesis, challenged males were characterized by transcriptional shifts away from self-maintenance, particularly in genes that function in DNA repair, cell death, muscle growth, and immune/inflammatory response. These results show that social challenges can cause rapid and lasting changes in gene expression in the periphery without a systemic change in the hormones that have been hypothesized to engender adaptive responses to social instability.
