Meeting Abstract

54.3  Tuesday, Jan. 6  Metabolically mediated oxidative stress and in a free-ranging mammal FLETCHER, Q.E.*; SELMAN, C.; SPEAKMAN, J.R.; LEEUWENBURGH, C.; HUMPHRIES, M.M.; McGill University; University of Aberdeen; University of Aberdeen; University of Florida; McGill University quinn.fletcher2@mail.mcgill.ca

Cumulative physiological damage is the underlying cause of senescence and it results because of the allocation trade-off between reproduction and somatic maintenance. Levels of metabolic expenditure are one possible measure of allocation to reproduction that may mediate this trade-off. In mammals, high levels of metabolic expenditure are necessary to wean offspring, but an unavoidable by-product of aerobic metabolism is the generation of reactive oxygen species which may lead to oxidative stress. The accumulation of oxidative stress is widely believed to mediate the rate of physiological aging. Here, we examine the effect of metabolic expenditure on levels of oxidative stress accumulated during reproduction. Research was conducted on a natural population of red squirrels in Yukon, Canada. Levels of oxidative stress were determined from plasma samples paired with measures of field metabolic rate. Overall, levels of oxidative stress were higher in lactating as compared to nonbreeding females, and there was a positive relationship between field metabolic rate and oxidative stress. In conclusion, our results suggest that metabolic expenditure may be the underlying mediator of the trade-off between reproductive output and the somatic damage that underlies aging.