Abstract
Ecologically-relevant factors such as exercise and diet quality can
directly influence how multifaceted physiological systems work; however,
little is known about how such factors directly and interactively affect
key components of the antioxidant system in multiple tissues of
migratory songbirds. We tested 3 main hypotheses across three tissues in
European Starlings fed diets with more or less antioxidants
(anthocyanins) and long-chain polyunsaturated fats (18:2n6) while being
flight-trained in a wind tunnel. Stimulatory effect of flight :
Flight-training stimulated the antioxidant system in that a) plasma
oxidative damage was reduced during a given acute flight, and b)
antioxidant capacity and oxidative damage in plasma and tissues of
flight-trained birds were similar to that of untrained birds.
Flight-trained birds that expended more energy per unit time (kJ/min)
during their longest, final flight decreased the non-enzymatic component
of their antioxidant system the most during the final flight.Dietary antioxidant effect : Flight-trained birds that consumed
more dietary anthocyanins had similar antioxidant capacity in liver and
flight-muscle compared to untrained birds, and oxidative damage was
prevented in the flight-muscle and reduced in the liver of
flight-trained birds compared to untrained birds. Dietary fat
quality effect: Contrary to our predictions, dietary 18:2n-6 did not
influence oxidative status even after flight training. We found limited
evidence that circulating and tissue-level oxidative capacity and damage
were tightly regulated in flight-trained starlings, in contrast to the
precise regulation on gene expression and enzyme activity that were
observed in companion studies. In sum, the antioxidant system of
songbirds flexibly responded to changes in availability of dietary
antioxidants as well as increased flight time and effort, and such
condition-dependent, individual-level, tissue-specific responses to the
oxidative costs of long-duration flights apparently requires recovery
periods for maintaining oxidative balance during migration.
Keywords migration, antioxidants, antioxidant capacity, dietary fat quality,
flight training, oxidative damage