title: Increased reactivity and monoamine dysregulation following stress in triploid Atlantic salmon (Salmo salar).
abstract: Artificial triploid salmonids are sterile and therefore commercially bred to prevent genetic interactions between wild and domestic fish strains. The full biological effects of having an extra chromosome set are largely unknown, but triploids are considered to be more sensitive to sub-optimal environmental conditions and to be stressed by the presence of diploid conspecifics. Brain serotonergic and dopaminergic activity are known to regulate the stress response in vertebrates, but monoamine systems in diploid and triploid fish have yet to be compared. Here we study monoamine neurochemistry in the telencephalon and brain stem of juvenile diploid and triploid Atlantic salmon (Salmo salar) in response to stress (unstressed vs stressed individuals) and holding (separate- vs mixed-ploidy) conditions. Both diploids and triploids showed an increase in serotonergic activity following stress, but the increase was significantly greater in the telencephalon of triploids compared to diploids. Furthermore, while telencephalic dopaminergic activity was significantly increased in diploids following stress, there was no response in triploids. Holding conditions had a significant effect on dopaminergic activity in the brain stem of diploids only, with lower values in mixed- compared to separate-ploidy conditions. These results suggest artificially produced triploids experience increased reactivity and monoaminergic dysregulation following stress that may impede their welfare and performance.
authors.affiliation: Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway. Electronic address: thomas.fraser@nmbu.no.
authors.forename: Thomas William Kenneth
authors.initials: TW
authors.lastname: Fraser
authors.affiliation: Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Vindas
authors.affiliation: Institute of Marine Research (IMR), Matre Research Station, Matredal, Norway.
authors.forename: Per Gunnar
authors.initials: PG
authors.lastname: Fjelldal
authors.affiliation: Department of Neuroscience, Uppsala University, Uppsala, Sweden.
authors.forename: Svante
authors.initials: S
authors.lastname: Winberg
authors.affiliation: Department of Neuroscience, Uppsala University, Uppsala, Sweden.
authors.forename: Per-Ove
authors.initials: PO
authors.lastname: Thörnqvist
authors.affiliation: Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Øverli
authors.affiliation: Institute of Marine Research (IMR), Bergen, Norway.
authors.forename: Jon-Egil
authors.initials: JE
authors.lastname: Skjæraasen
authors.affiliation: Institute of Marine Research (IMR), Matre Research Station, Matredal, Norway.
authors.forename: Tom Jonny
authors.initials: TJ
authors.lastname: Hansen
authors.affiliation: Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
authors.forename: Ian
authors.initials: I
authors.lastname: Mayer
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000378:metabolism; D005260:Female; D008297:Male; D020317:Salmo salar / Q000235:genetics / Q000378:metabolism*; D059326:Serotonergic Neurons / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D013312:Stress, Physiological; D013687:Telencephalon / Q000166:cytology / Q000378:metabolism; D057885:Triploidy
chemical_list: D012701:Serotonin; D004298:Dopamine
keywords: Dopamine; Neuroendocrine; Ploidy; Serotonin; Telencephalon