title: Short-term and long-term effects of transient exogenous cortisol manipulation on oxidative stress in juvenile brown trout.
abstract: In the wild, animals are exposed to a growing number of stressors with increasing frequency and intensity, as a result of human activities and human-induced environmental change. To fully understand how wild organisms are affected by stressors, it is crucial to understand the physiology that underlies an organism's response to a stressor. Prolonged levels of elevated glucocorticoids are associated with a state of chronic stress and decreased fitness. Exogenous glucocorticoid manipulation reduces an individual's ability to forage, avoid predators and grow, thereby limiting the resources available for physiological functions like defence against oxidative stress. Using brown trout (Salmo trutta), we evaluated the short-term (2 weeks) and long-term (4 months over winter) effects of exogenous cortisol manipulations (versus relevant shams and controls) on the oxidative status of wild juveniles. Cortisol caused an increase in glutathione over a 2 week period and appeared to reduce glutathione over winter. Cortisol treatment did not affect oxidative stress levels or low molecular weight antioxidants. Cortisol caused a significant decrease in growth rates but did not affect predation risk. Over-winter survival in the stream was associated with low levels of oxidative stress and glutathione. Thus, oxidative stress may be a mechanism by which elevated cortisol causes negative physiological effects.
authors.affiliation: Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6 kbir@aqua.dtu.dk.|Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.|DTU AQUA, National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Technical University of Denmark, Vejlsøvej 39, Silkeborg 8600, Denmark.
authors.forename: Kim
authors.identifier: 0000-0001-9242-0560
authors.initials: K
authors.lastname: Birnie-Gauvin
authors.affiliation: Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Peiman
authors.affiliation: DTU AQUA, National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Technical University of Denmark, Vejlsøvej 39, Silkeborg 8600, Denmark.|Danish Centre for Wild Salmon, Brusgårdsvej 15, Randers 8960, Denmark.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Larsen
authors.affiliation: DTU AQUA, National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Technical University of Denmark, Vejlsøvej 39, Silkeborg 8600, Denmark.
authors.forename: Kim
authors.initials: K
authors.lastname: Aarestrup
authors.affiliation: Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: William G
authors.initials: WG
authors.lastname: Willmore
authors.affiliation: Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Cooke
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D003718:Denmark; D005978:Glutathione / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology*; D018384:Oxidative Stress; D012621:Seasons; D014337:Trout / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005978:Glutathione; D006854:Hydrocortisone
keywords: Antioxidants; Glucocorticoids; Glutathione; Oxidative ecology; Reactive oxygen species; Salmo trutta