title: Carotenoids, birdsong and oxidative status: administration of dietary lutein is associated with an increase in song rate and circulating antioxidants (albumin and cholesterol) and a decrease in oxidative damage.
abstract: Despite the appealing hypothesis that carotenoid-based colouration signals oxidative status, evidence supporting the antioxidant function of these pigments is scarce. Recent studies have shown that lutein, the most common carotenoid used by birds, can enhance the expression of non-visual traits, such as birdsong. Nevertheless, the underlying physiological mechanisms remain unclear. In this study we hypothesized that male European starlings (Sturnus vulgaris) fed extra lutein increase their song rate as a consequence of an improved oxidative status. Although birdsong may be especially sensitive to the redox status, this has, to the best of our knowledge, never been tested. Together with the determination of circulating oxidative damage (ROMs, reactive oxygen metabolites), we quantified uric acid, albumin, total proteins, cholesterol, and testosterone, which are physiological parameters potentially sensitive to oxidation and/or related to both carotenoid functions and birdsong expression. We found that the birds fed extra lutein sang more frequently than control birds and showed an increase of albumin and cholesterol together with a decrease of oxidative damage. Moreover, we could show that song rate was associated with high levels of albumin and cholesterol and low levels of oxidative damage, independently from testosterone levels. Our study shows for the first time that song rate honestly signals the oxidative status of males and that dietary lutein is associated with the circulation of albumin and cholesterol in birds, providing a novel insight to the theoretical framework related to the honest signalling of carotenoid-based traits.
authors.affiliation: Department of Biology, Ethology Group, University of Antwerp, Campus Drie Eiken, Antwerp, Belgium.
authors.forename: Stefania
authors.initials: S
authors.lastname: Casagrande
authors.affiliation: Department of Biology, Ethology Group, University of Antwerp, Campus Drie Eiken, Antwerp, Belgium; Institute for Education and Information Sciences, Research Unit Didactica, University of Antwerp, Antwerp, Belgium.
authors.forename: Rianne
authors.initials: R
authors.lastname: Pinxten
authors.affiliation: Department of Biology, Ethology Group, University of Antwerp, Campus Drie Eiken, Antwerp, Belgium.
authors.forename: Erika
authors.initials: E
authors.lastname: Zaid
authors.affiliation: Department of Biology, Ethology Group, University of Antwerp, Campus Drie Eiken, Antwerp, Belgium.
authors.forename: Marcel
authors.initials: M
authors.lastname: Eens
mesh_terms: D000418:Albumins / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism / Q000502:physiology*; D002784:Cholesterol / Q000378:metabolism; D004032:Diet; D014975:Lutein / Q000097:blood / Q000494:pharmacology; D008297:Male; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D046749:Starlings / Q000378:metabolism / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism; D014527:Uric Acid / Q000378:metabolism; D014828:Vocalization, Animal
chemical_list: D000418:Albumins; D000975:Antioxidants; D017382:Reactive Oxygen Species; D014527:Uric Acid; D002338:Carotenoids; D013739:Testosterone; D002784:Cholesterol; D014975:Lutein