title: Oxidative costs of reproduction: Oxidative stress in mice fed standard and low antioxidant diets.
abstract: Lactation is one of the most energetically expensive behaviours, and trade-offs may exist between the energy devoted to it and somatic maintenance, including protection against oxidative damage. However, conflicting data exist for the effects of reproduction on oxidative stress. In the wild, a positive relationship is often observed, but in laboratory studies oxidative damage is often lower in lactating than in non-breeding animals. We hypothesised that this discrepancy may exist because during lactation food intake increases many-fold resulting in a large increase in the intake of dietary antioxidants which are typically high in laboratory rodent chow where they are added as a preservative. We supplied lactating and non-breeding control mice with either a standard or low antioxidant diet and studied how this affected the activity of endogenous antioxidants (catalase, superoxide dismutase; SOD, and glutathione peroxidise; GPx) and oxidative damage to proteins (protein carbonyls, PC) in liver and brain tissue. The low antioxidant diet did not significantly affect activities of antioxidant enzymes in brain or liver, and generally did not result in increased protein damage, except in livers of control mice on low antioxidant diet. Catalase activity, but not GPx or SOD, was decreased in both control and lactating mice on the low antioxidant diet. Lactating mice had significantly reduced oxidative damage to both liver and brain compared to control mice, independent of the diet they were given. In conclusion, antioxidant content of the diet did not affect oxidative stress in control or reproductive mice, and cannot explain the previously observed reduction in oxidative stress in lactating mammals studied in the laboratory. The reduced oxidative stress in the livers of lactating mice even under low antioxidant diet treatment was consistent with the 'shielding' hypothesis.
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: L M
authors.initials: LM
authors.lastname: Vaanholt
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: A
authors.initials: A
authors.lastname: Milne
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: C
authors.initials: C
authors.lastname: Hambly
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: S E
authors.initials: SE
authors.lastname: Mitchell
authors.affiliation: University of Veterinary Medicine in Vienna, Department of Integrative Biology and Evolution, Vienna, Austria.
authors.forename: T G
authors.initials: TG
authors.lastname: Valencak
authors.affiliation: Nutrition Obesity Research Center, The University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Allison
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK; Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. Electronic address: j.speakmant@abdn.ac.uk.
authors.forename: J R
authors.initials: JR
authors.lastname: Speakman
mesh_terms: D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D015992:Body Mass Index; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D007774:Lactation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D050050:Protein Carbonylation / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects* / Q000502:physiology; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors
chemical_list: D000975:Antioxidants; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione
keywords: Endogenous antioxidants; Lactation; Oxidative damage