SREL Reprint #3446

Dietary selenomethionine administration and its effects on the American alligator (Alligator mississippiensis): oxidative status and corticosterone levels

John W. Finger Jr.1,2,3, Matthew T. Hamilton2, Meghan D. Kelley3, Yufeng Zhang3,4, Andreas N. Kavazis5, Travis C. Glenn1, and Tracey D. Tuberville2

1Department of Environmental Health Science, University of Georgia, Athens, GA 30602, USA
2Savannah River Ecology Laboratory, University of Georgia, PO Drawer E, Aiken, SC 29802, USA
3Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
4Buck Institute for Research on Aging, Novato, CA 94945, USA
5School of Kinesiology, Auburn University, Auburn, AL 36849, USA

Abstract: Selenium (Se) is an essential nutrient which in excess causes toxicity. The disposal of incompletely combusted coal, which often is rich in Se, into aquatic settling basins is increasing the risk of Se exposure worldwide. However, very few studies have looked at the physiological effects of Se exposure on long-lived, top trophic vertebrates, such as the American alligator (Alligator mississippiensis). During a 7-week period, alligators were fed one of three dietary treatments: mice injected with deionized water or mice injected with water containing 1000 or 2000 ppm selenomethionine (SeMet). One week after the last feeding alligators were bled within 3 min of capture for plasma corticosterone (CORT). A few days later, all alligators were euthanized and whole blood and tail tissue were harvested to measure oxidative damage, an antioxidant-associated transcription factor, and antioxidant enzymes [glutathione peroxidase-1 (GPX1), superoxide dismutase-1 (SOD1), and SOD2] by Western blotting. There was a dose-dependent increase in baseline CORT levels in alligators administered SeMet. Except for blood SOD2 levels, SeMet treatment had no effect (p > 0.05 for all) on oxidative status: oxidative damage, GPX1, SOD1, and muscle SOD2 levels were similar among treatments. Our results illustrate that high levels of Se may act as a stressor to crocodilians. Future studies should investigate further the physiological effects of Se accumulation in long-lived, top-trophic vertebrates.

SREL Reprint #3446

Finger Jr., J. W., M. T. Hamilton, M. D. Kelley, Y. Zhang, A. N. Kavazis, T. C. Glenn, and T. D. Tuberville. 2018. Dietary selenomethionine administration and its effects on the American alligator (Alligator mississippiensis): oxidative status and corticosterone levels. Archives of Environmental Contamination and Toxicology 75(1): 37-44.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).