Maturation increases superoxide radical production without increasing oxidative damage in the skeletal muscle of hooded seals

Diving vertebrates represent unique models for the study of the physiological responses to reactive oxygen species (ROS) production and oxidative stress because of their adaptability to cope with dive-derived ROS production. We hypothesized that in the skeletal muscle of a diving mammal, the hooded seal (Cystophora cristata (Erxleben, 1777)), ROS production increases with maturation but the accumulation of oxidative damage does not. To test this, we analyzed the tissue capacity to produce ROS, the accumulation of oxidative damage, and the activity and protein content of the cooper, zinc, and manganese dependent superoxide dismutases (Cu, ZnSOD, MnSOD) in skeletal muscle from neonates, weaned pups, and adult hooded seals. Our results showed higher tissue capacity to produce ROS, higher Cu, ZnSOD and MnSOD activities, and higher MnSOD protein content in adult seals than in pups. No differences in oxidative damage to lipids, proteins, or DNA were detected among groups. Results suggest that increased SOD activity likely counters the oxidative damage commonly associated with increased ROS production. These findings highlight the unusual tolerance of skeletal muscle of seals to increased ROS production. Les vertebras plongeurs sont des modeles uniques pour l'etude des reactions physiologiques a la production d'especes d'oxygene reactif (ROS) et du stress oxydatif a cause de leur adaptabilite pour faire face a la production de ROS produits durant la plongee. Nous eemettons l'hypothese selon laquelle, dans le muscle squelettique du phoque a capuchon (Cystophora cristata (Erxleben, 1777)), la production de ROS augmente en fonction de la maturation, mais non l'accumulation de dommages oxydatifs. Afin de tester l'hypothese, nous analysons la capacite du tissu a produire des ROS, l'accumulation de dommages oxydatifs, ainsi que l'activite et le contenu proteinique des superoxydes dismutases dependantes du cuivre, du zinc et du manganese (Cu, ZnSOD, MnSOD) dans le muscle squelettique chez des phoques a capuchon nouveau nes, des petits sevres et des adultes. Les tissus ont une plus forte capacite; de production de ROS et possedent des activites plus eleveees de Cu,ZnSOD et de MnSOD et des contenus proteiniques plus importants de MnSOD chez les phoques adultes que chez les petits. Aucune difference n'a pu etre deecelee entre les groupes dans les dommages oxydatifs aux lipides, aux proteines et a l'ADN. Nos resultats laissent croire que l'activite; accrue des SOD bloque vraisemblablement les dommages oxydatifs couramment associesa la production plus eelevee de ROS. Ces observations soulignent la tolerance exceptionnelle du muscle squelettique des phoques a la production accrue de ROS. [Traduit par la Redaction]
Introduction Oxygen consumption by animal cells is essential for the production of the energy needed to maintain cellular functions and metabolic activity. Paradoxically, oxygen-mediated ATP production via the electron transport [...]