Effects of acute and chronic stress on telencephalic neurochemistry and gene expression in rainbow trout (Oncorhynchus mykiss)

Research output: Contribution to journalArticle

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 (CRFBP), CRF receptors (CRFR1 and CRFR2), mineralocorticoid receptor (MR), glucocorticoid receptors (GR1 and GR2) and serotonin type 1A (5-HT1A) receptors (5-HT1Aα and 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-3 for 28 days. Generally, being held at 140 kg m-3 resulted 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-HT1Aα and 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.

Details

Authors
  • Maria Moltesen
  • Danielle Caroline Laursen
  • Per Ove Thörnqvist
  • Madelene Åberg Andersson
  • Svante Winberg
  • Erik Höglund
Organisations
External organisations
  • Uppsala University
  • University of Copenhagen
  • Technical University of Denmark
  • Norwegian Institute for Water Research
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Behavioral Sciences Biology
  • Other Chemistry Topics

Keywords

  • 5-HT, Allostatic load, Cortisol, Gene expression, HPI axis, Neurochemistry
Original languageEnglish
Pages (from-to)3907-3914
Number of pages8
JournalJournal of Experimental Biology
Volume219
Issue number24
Publication statusPublished - 2016 Dec 15
Publication categoryResearch
Peer-reviewedYes