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Glucocorticoids (GCs) are metabolic hormones that promote catabolic
processes, which release stored energy and support high metabolic demands
such as during prolonged flights of migrating birds. Dietary antioxidants
(e.g., anthocyanins) support metabolism by quenching excess reactive
oxygen species produced during aerobic metabolism, and also by activating
metabolic pathways that, similar to GCs’ function, release stored energy,
although the extent of complementarity between GCs and dietary
antioxidants is not well known. If anthocyanins complement GCs functions,
birds consuming anthocyanin-rich food can be expected to limit the
secretion of GCs when coping with a metabolically challenging activity,
avoiding the exposure to potential hormonal detrimental effects. We tested
this hypothesis in European starlings (Sturnus vulgaris) flying in a
windtunnel. We compared levels of corticosterone, the main avian GCs,
immediately after a sustained flight and at rest for birds that were fed
diets with or without an anthocyanin supplement. As predicted, we found
(1) higher corticosterone after flight than at rest in both diet groups,
and (2) anthocyanin-supplemented birds had less elevated corticosterone
after flight than unsupplemented control birds. This provides novel
evidence that dietary antioxidants attenuate the activation of the HPA
axis (i.e. increased secretion of corticosterone) during long-duration
flight.
148 views reported since publication in 2020.