Meeting Abstract
Vertebrates respond to stress by activating a suite of integrated physiological response mechanisms, of which a key component is the hypothalamic-pituitary-adrenal (HPA) axis. When activated, this stress response results in the release of glucocorticoids (GCs), causing an increase from baseline levels to stress-induced levels. As homeostasis is restored, GCs decrease toward baseline, and this is referred to as recovering levels. There is considerable individual variation in these three components of a stress response, and because GCs have extensive and variable effects on physiology, this individual variation can correlate with fitness. One potential consequence of a stress response is that exposure to GCs can increase oxidative stress levels. We used Japanese quail (Coturnix japonica) to explore how variation in an individual’s stress response affects oxidative stress. Specifically, we determined how baseline, stress-induced, and recovering levels of GCs associate with baseline measures of oxidative stress (total antioxidant capacity, TAC; reactive oxygen metabolites, ROMs). We found that baseline and recovering GC levels both positively correlated to ROMs, while stress-induced GC levels did not associate with ROMs. No measure of GCs correlated with TAC levels. Because baseline GC levels reflect predictable energetic demands, our results suggest that individuals that expend more energy daily also have higher oxidative stress levels. In addition, those individuals that have a protracted GC recovery after an acute stress response are also prone to higher levels of oxidative stress, possibly due to prolonged exposure to high levels of GCs during an acute stress response.
