Meeting Abstract
Chronic stress has been extensively studied in both the laboratory and field. What remains unknown is whether and how recovery periods between episodes of chronic stress influence these responses. This is a crucial question because animals are often exposed to chronic stress and it’s important to understand if the effects of these situations can be alleviated. To test this, we exposed house sparrows (Passer domesticus) to two bouts of a chronic stress protocol that consisted of random, repeated stressors. Birds were assigned to treatment groups that differed in the amount of recovery time between the two sets of chronic stress—0 hours, 24 hours, 72 hours, or 144 hours. Blood samples and video recordings were taken before the experiment, before and after the recovery periods, and after the second bout of chronic stress. Video analysis assessed changes in perch hopping activity. Blood samples assessed changes in baseline and stress-induced corticosterone (Cort), Cort negative feedback strength, immune function, and uric acid concentrations. We found no significant differences in any recovery group in baseline or stress-induced Cort, but birds failed to shut down the release of Cort after receiving 24 hours of recovery. While recovery length did not affect uric acid concentrations, chronic stress tended to increase it. Bacterial killing capacity decreased in birds that received 0, 72, or 144 hours, but remained the same in birds that recovered for 24 hours. Finally, perch hopping tended to increase during the first round of stressors and decrease in the second round of stressors. These data suggest that recovery periods do influence physiology and behavior, but don’t necessarily “reset” the animals.
