Meeting Abstract
Corticosterone (Cort) is the metric of choice in stress physiology studies. Despite its popularity, this hormone often does not accurately reflect how an animal copes with a stressor, likely due to its complex actions. Furthermore, changes in Cort are rarely consistent across contexts, life-history stages, and species. By focusing solely on this hormone, we reach an incomplete picture of how animals cope with unpredictable stimuli; a separate, independent measure is thus needed. In this study, we tested the hypothesis that acute increases in DNA damage could serve as an adjunct to Cort when assessing stressor exposure. Previous studies have found that DNA damage increases in response to stress-related hormones in vitro, prompting further exploration in wild animal systems. We exposed house sparrows (Passer domesticus) to a short (30 or 120-minute) restraint stressor and took blood samples at 0, 30, 60, and 120 minutes to measure Cort, DNA damage, and uric acid. DNA damage and Cort increased while uric acid decreased. DNA damage can thus reflect acute stressor exposure. We also tested the impacts of freezing on DNA damage in the hopes that this method will become more applicable in field-based studies. Leaving red blood cells on ice for up to 24 hours resulted in statistically significant, but likely not important, increases in DNA damage. Freezing blood samples for up to 4 weeks substantially increased DNA damage. These findings emphasize the importance of assaying samples together whenever possible. Overall, these results indicate that DNA damage can reflect whether and how an animal is coping with a stressor.
