Effects of carotenoid and vitamin E supplementation on oxidative stress and plumage coloration in house finches (Haemorhous mexicanus) Mathieu Giraudeau ⁎, Karen Sweazea, Michael W. Butler 1 , Kevin J. McGraw Arizona State University, School of Life Sciences, Tempe, AZ 85287-4501, USA abstract article info Article history: Received 6 May 2013 Received in revised form 9 July 2013 Accepted 9 July 2013 Available online 17 July 2013 Keywords: Carotenoids Oxidative damage Tocopherol Coloration House finch There has been much recent interest from both applied and basic scientists in the broad series of benefits that animals reap from acquiring high concentrations of dietary antioxidants, such as carotenoids and vitamins (e.g., vitamin E, or tocopherol). Most attention has been paid to separate effects of these compounds on, for example, coloration, health state, development, and vision, but because of possible interactions between these lipid-soluble molecules, we are in need of more studies that co-manipulate these substances and examine their possible synergistic impacts on animal physiology and phenotype. We capitalized on a model avian system (the house finch, Haemorhous mexicanus), where extensive information is available on the fitness roles of carotenoids, to test how variation in carotenoid and/or vitamin E concentrations in the diet impacts body accumulation of these compounds, factors related to oxidative damage (e.g., breast muscle and plasma oxidative-stress susceptibility, plasma nitric-oxide levels), and plumage color development. As in a previous study of ours on carotenoids and health in finches, we employed a 2 × 2 factorial experimental design on birds in both molting and non-molting conditions, to understand how seasonal shifts in carotenoid use (i.e., pigment incorporation into plumage) might alter the accumulation and roles of carotenoids and vitamins. As expected, lutein supplementation increased the level of circulating carotenoids in both experiments and the color of newly molted plumage. By contrast, vitamin E provisioning did not significantly affect plasma carotenoid levels or plumage coloration in either experiment. Interestingly, carotenoid provisioning decreased circulating vitamin E levels during molt, which suggests either molecular competition between carotenoids and tocopherol at the absorption/transport stages or that vitamin E serves as an antioxidant to offset harmful actions that carotenoids may have at very high concentrations. Finally, in both experiments, we found a reduc- tion in breast-muscle oxidative damage for tocopherol-supplemented birds, which constitutes the first demon- stration of a protective effect of vitamin E against oxidative stress in wild birds. Taken together, these findings provide an interesting contrast with our earlier work on season-specific physiological benefits of carotenoids in finches and point to complex associations between indicators of antioxidant and oxidative state in wild- caught animals. © 2013 Elsevier Inc. All rights reserved. 1. Introduction Minimizing oxidative damage to cells and tissues is a major physio- logical challenge to organisms. Animals employ various antioxidant mechanisms to offset oxidative stressors (Surai, 2002), including both endogenous (e.g., hormone-initiated cellular processes, enzymatic) and exogenous sources (e.g., dietary vitamins, carotenoids) of detoxifi- cation (McGraw et al., 2011). Though there has been extensive work on oxidative balance under controlled laboratory conditions, relatively little is known about the costs and benefits of antioxidants in free- ranging organisms (Cohen et al., 2008; Nussey et al., 2009; McGraw et al., 2010). Among the various antioxidant systems to study, carotenoids have received particular attention in the last two decades, largely because these pigments also conspicuously color the integument of animals (e.g., bird feathers, fish scales; McGraw, 2006). Carotenoid colors are used widely as condition-dependent signals of quality (e.g., nutrition, health; Hill, 2006), and it naturally follows that carotenoid pigmenta- tion may specifically reflect an individual's antioxidant status (von Schantz et al., 1999). However, there are few direct studies on this topic, and those that have been conducted have yielded ambiguous re- sults and even spawned new hypotheses. Though one of the first tests found that circulating carotenoid levels and antioxidant defenses were significantly positively correlated in zebra finches (Taeniopygia guttata) (Alonso-Alvarez et al., 2004), Costantini and Moller (2008) showed in a Comparative Biochemistry and Physiology, Part A 166 (2013) 406–413 ⁎ Corresponding author. Tel.: +1 480 727 9094; fax: +1 480 965 6899. E-mail address: giraudeau.mathieu@gmail.com (M. Giraudeau). 1 Current address: Lafayette College, Department of Biology, Easton, PA 18042-1776, USA. 1095-6433/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cbpa.2013.07.014 Contents lists available at ScienceDirect Comparative Biochemistry and Physiology, Part A journal homepage: www.elsevier.com/locate/cbpa