title: Effects of acute and chronic stress on telencephalic neurochemistry and gene expression in rainbow trout (Oncorhynchus mykiss).
abstract: By filtering relevant sensory inputs and initiating stress responses, the brain is an essential organ in stress coping and adaptation. However, exposure to chronic or repeated stress can lead to allostatic overload, where neuroendocrinal and behavioral reactions to stress become maladaptive. This work examines forebrain mechanisms involved in allostatic processes in teleost fishes. Plasma cortisol, forebrain serotonergic (5-HTergic) neurochemistry, and mRNA levels of corticotropin-releasing factor (CRF), CRF-binding protein (CRF-BP), CRF receptors (CRFR1 and CRFR2), mineralocorticoid receptor (MR), glucocorticoid receptors (GR1 and GR2) and serotonin type 1A (5-HT1A) receptors (5-HT1Aαand 5-HT1Aβ) were investigated at 1 h before and 0, 1 and 4 h after acute stress, in two groups of rainbow trout held in densities of 25 and 140 kg m-3for 28 days. Generally, being held at 140 kg m-3resulted in a less pronounced cortisol response. This effect was also reflected in lower forebrain 5-HTergic turnover, but not in mRNA levels in any of the investigated genes. This lends further support to reports that allostatic load causes fish to be incapable of mounting a proper cortisol response to an acute stressor, and suggests that changes in forebrain 5-HT metabolism are involved in allostatic processes in fish. Independent of rearing densities, mRNA levels of 5-HT1Aαand MR were downregulated 4 h post-stress compared with values 1 h post-stress, suggesting that these receptors are under feedback control and take part in the downregulation of the hypothalamic-pituitary-interrenal (HPI) axis after exposure to an acute stressor.
authors: Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, Building 3, 4th Floor, Copenhagen Ø DK-2100, Denmark.|Section for Aquaculture, Institute for Aquatic Resources, Danish Technical University, P.O. Box 101, Hirtshals DK-9850, Denmark.
authors: Maria
authors: M
authors: Moltesen
authors: Section for Aquaculture, Institute for Aquatic Resources, Danish Technical University, P.O. Box 101, Hirtshals DK-9850, Denmark.
authors: Danielle Caroline
authors: DC
authors: Laursen
authors: Department of Neuroscience, Uppsala University, P.O. Box 593, Uppsala SE-75124, Sweden.
authors: Per-Ove
authors: PO
authors: Thörnqvist
authors: Chemical Biology and Therapeutics, Department of Experimental Medical Science, Lund University, P.O. Box 188, Lund SE-22100, Sweden.
authors: Madelene Åberg
authors: MÅ
authors: Andersson
authors: Department of Neuroscience, Uppsala University, P.O. Box 593, Uppsala SE-75124, Sweden.
authors: Svante
authors: S
authors: Winberg
authors: Section for Aquaculture, Institute for Aquatic Resources, Danish Technical University, P.O. Box 101, Hirtshals DK-9850, Denmark erik.hoglund@niva.no.|Norwegian Institute for Water Research, NIVA, Gaustadalléen 21NO-0349, Oslo, Norway.
authors: Erik
authors: 0000-0002-1350-8255
authors: E
authors: Höglund
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation; D006854:Hydrocortisone / Q000097:blood; D009448:Neurochemistry; D017686:Oncorhynchus mykiss / Q000097:blood / Q000235:genetics* / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D012701:Serotonin / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics*; D013687:Telencephalon / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D012701:Serotonin; D006854:Hydrocortisone
keywords: 5-HT; Allostatic load; Cortisol; Gene expression; HPI axis; Neurochemistry