Meeting Abstract

P1.112  Friday, Jan. 4  Oxidative stress in fasting adult breeding northern elephant seals SHARICK, JT*; VAZQUES-MEDINA, JP; ORTIZ, RM; CROCKER, DE; Sonoma State Univ.; Univ. of California, Merced; Univ. of California, Merced; Sonoma State Univ. jeffsharick@gmail.com

Prolonged fasting is associated with oxidative stress including increases in the production of reactive oxygen species, oxidative damage and inflammation. Oxidative stress mechanisms in fasting-adapted species are not well understood. Elephant seals undergo prolonged fasts while maintaining high metabolic rates, particularly during breeding. Weaned pups undergoing developmental fasts up-regulate anti-oxidant enzymes to levels that are sufficient to avoid oxidative damage. We measured plasma changes in the activity of the oxidant producing protein, xanthine oxidase (XO), oxidative damage and inflammatory markers and antioxidant enzymes in 30 adult male and 35 adult female northern elephant seals across a 1-3 month breeding fast. XO levels, a marker for pro-oxidant stress, were high and increased across the fast in both sexes. Anti-oxidant enzymes, catalase and glutathione peroxidase, increased in both sexes. With the exception of nitrotyrosine (NT), a marker for protein oxidation, plasma markers of damage or inflammation did not change in females. Plasma markers of lipid peroxidation (8-isoprostanes and 4-hydroxynonenal) and inflammation (tumor necrosis factor-α) increased across the fast for males. In contrast, plasma NT levels declined in males. XO, damage and inflammatory markers and antioxidant enzymes were strongly correlated in males but these relationships were weaker in females. These data suggest strong anti-oxidant responses during fasting. Oxidative stress associated with the longer (3 month) fast in males may exceed these responses creating oxidative damage as a physiological cost of breeding. Anti-oxidant responses in females appear to prevent damage or inflammation during the 1 month fast.