title: Migratory refueling affects non-enzymatic antioxidant capacity, but does not increase lipid peroxidation.
abstract: All aerobic organisms are to some degree affected by oxidative stress, which is an imbalance between pro-oxidants and antioxidants in favor of the former. Pro-oxidants can damage DNA, proteins and lipids, and as such oxidative stress can carry considerably fitness costs. In mammals excessive calorie intake is a known cause of oxidative stress. We investigated whether in migrant birds, which typically engage in over-eating in between flights (refueling), high food intake causes oxidative stress. In an experiment we compared levels of plasmatic total non-enzymatic antioxidant capacity (AOX) and oxidative damage (lipid peroxidation) between migrants repeatedly fasted and refed (simulating the flight-refuel cycle of wild migrants), and migrants on ad libitum food. We found that refueling increased AOX, an effect mainly attributable to an increase in uric acid level, an antioxidant that is produced during protein metabolism. Accordingly, variation in AOX was mainly explained by the refueling birds' food intake. However, food intake in migrants on ad libitum food did not explain any variation in AOX. Refueling did not affect lipid peroxidation, nor were its levels explained by food intake. We propose that over-eating migrants retain uric acid, which might be a very low cost mechanism to forego oxidative damage.
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany. Electronic address: cas.eikenaar@ifv-vogelwarte.de.
authors.forename: Cas
authors.initials: C
authors.lastname: Eikenaar
authors.affiliation: Department of Biology, Lund University, SE-22362 Lund, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Jönsson
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Fritzsch
authors.affiliation: Department of Biology, Lund University, SE-22362 Lund, Sweden.
authors.forename: Hong-Lei
authors.initials: HL
authors.lastname: Wang
authors.affiliation: Department of Biology, Lund University, SE-22362 Lund, Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Isaksson
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001717:Birds; D004435:Eating / Q000502:physiology*; D015227:Lipid Peroxidation / Q000502:physiology*; D008315:Malondialdehyde / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D014527:Uric Acid / Q000378:metabolism
chemical_list: D000975:Antioxidants; D014527:Uric Acid; D008315:Malondialdehyde
keywords: Experiment; Food intake; Migration; Oxidative stress; Refueling; Wheatear