title: Altered burst swimming in rainbow trout Oncorhynchus mykiss exposed to natural and synthetic oestrogens.
abstract: Juvenile rainbow trout Oncorhynchus mykiss were exposed to two concentrations each of 17β-oestradiol (E2; natural oestrogen hormone) or 17α-ethinyl oestradiol (EE2; a potent synthetic oestrogen hormone) to evaluate their potential effects on burst-swimming performance. In each of six successive burst-swimming assays, burst-swimming speed (Uburst ) was lower in fish exposed to 0.5 and 1 µg l(-1) E2 and EE2 for four days compared with control fish. A practice swim (2 days prior to exposure initiation) in control fish elevated initial Uburst values, but this training effect was not evident in the 1 µg l(-1) EE2-exposed fish. Several potential oestrogen-mediated mechanisms for Uburst reductions were investigated, including effects on metabolic products, osmoregulation and blood oxygen-carrying capacity. Prior to burst-swimming trials, fish exposed to E2 and EE2 for 4 days had significantly reduced erythrocyte numbers and lower plasma glucose concentrations. After six repeated burst-swimming trials, plasma glucose, lactate and creatinine concentrations were not significantly different among treatment groups; however, plasma Cl(-) concentrations were significantly reduced in E2- and EE2-treated fish. In summary, E2 and EE2 exposure altered oxygen-carrying capacity ([erythrocytes]) and an osmoregulatory-related variable ([Cl(-) ]), effects that may underlie reductions in burst-swimming speed, which will have implications for fish performance in the wild.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnabya, British Columbia V5A 1S6, Canada.
authors.forename: H L
authors.initials: HL
authors.lastname: Osachoff
authors.forename: K N
authors.initials: KN
authors.lastname: Osachoff
authors.forename: A E
authors.initials: AE
authors.lastname: Wickramaratne
authors.forename: E K
authors.initials: EK
authors.lastname: Gunawardane
authors.forename: F P
authors.initials: FP
authors.lastname: Venturini
authors.forename: C J
authors.initials: CJ
authors.lastname: Kennedy
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002712:Chlorides / Q000032:analysis; D004781:Environmental Exposure; D004912:Erythrocytes / Q000187:drug effects; D004958:Estradiol / Q000032:analysis*; D004997:Ethinyl Estradiol / Q000032:analysis*; D006400:Hematocrit; D006854:Hydrocortisone / Q000097:blood; D017686:Oncorhynchus mykiss / Q000502:physiology*; D005082:Physical Exertion; D013550:Swimming; D014819:Vitellogenins / Q000097:blood; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D001786:Blood Glucose; D002712:Chlorides; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D004958:Estradiol; D006854:Hydrocortisone
keywords: 17α-ethinyl oestradiol; 17β-oestradiol; chloride; erythrocytes; glucose; osmoregulation