Loss of integration is associated with reduced resistance to oxidative stress

Abstract

SUMMARYOne cellular mechanism thought to be particularly important as a constraint on lifespan and life-history strategies is oxidative stress. Susceptibility to oxidative stress is influenced by a number of antioxidant defences, whose effectiveness depends on the synergistic and competitive interactions among them (biochemical integration). It is generally assumed that exposure to oxidative stress is detrimental, but it is also possible that low level oxidative stress has a positive effect on integration, and therefore carries some benefits. Using three experimental groups of zebra finches (control, mild and high flight activity), we tested whether exercise-induced oxidative stress altered the integration of the pro-oxidant/antioxidant system by manipulating levels of flight activity, known to generate oxidative stress in birds. We show for the first time that a short-term high level of physical activity leads to a reduction in integration among components of the blood antioxidant defences, associated with a reduced resistance to oxidative stress. We found no evidence of improved integration in the antioxidant defences at low levels of oxidative stress exposure, suggesting that improved integration is not the route whereby any benefits of low level stress exposure occur. These findings point to a reduction in biochemical integration as a potential mechanism explaining a reduced resistance to oxidative stress induced by short-term stressors. Supplementary material available online at

Is oxidative status influenced by dietary carotenoid and physical activity after moult in the great tit (Parus major)?

“…Indeed, in zebra finches, when flight activity in a test cage was increased by moving perches over a period of 2 h, immediate ROM concentration increased but there was no change in antioxidant capacity, as measured by the concentration of antioxidant enzymes (Costantini et al, 2013). In the present study, flight activity was increased by plucking three primary feathers from each wing.…”

“…A previous study conducted on birds showed that flight activity increases ROM concentration (Costantini et al, 2013). Indeed, in zebra finches, when flight activity in a test cage was increased by moving perches over a period of 2 h, immediate ROM concentration increased but there was no change in antioxidant capacity, as measured by the concentration of antioxidant enzymes (Costantini et al, 2013).…”

Repeated exposure to stressful conditions can have beneficial effects on survival

“…In a recent study by Costantini and collaborators (2014) (see also Costantini et al 2013), adult zebra finches exposed to short episodes of heat stress in adulthood showed increased long-term survival and resilience only if they had been previously exposed to thermal stress before reaching sexual maturity. Since in our study, the birds continued to experience the food shortage throughout the period when survival was monitored, it seems likely that the protracted exposure to unpredictable food may have triggered hormetic responses, behavioural and/or physiological that increased likelihood of survival and, at least to some extent, prolonged lifespan.…”

The role of the antioxidant system during intense endurance exercise: lessons from migrating birds

“…Accordingly, plasma non-enzymatic antioxidants were higher in great tits (Parus major) with clipped feathers (which increases flight effort) than in individuals with unclipped feathers (Vaugoyeau et al, 2015). Interestingly, zebra finches (Taeniopygia guttata) flown at rapid speeds had increased levels of plasma uric acid but not antioxidant enzymes compared with those of control birds (Costantini et al, 2013). Many studies have shown that uric acid levels increase during flapping flight and migration.…”