Michail Pavlidis
Antonia Theodoridi
Aleka Tsalafouta
Progress in Neuro-Psychopharmacology & Biological Psychiatry 60:p 121-131, July 3, 2015. | DOI: 10.1016/j.pnpbp.2015.02.014
The main objectives of this study were to investigate the dynamics of the cortisol stress response and the underlying molecular regulation in adult zebrafish exposed to acute and long-term stressors that differed in nature, duration and relative intensity. Fish showed a very rapid and prolonged increase in trunk cortisol concentrations, starting at around 15 min and returning to basal levels at around 2 h following exposure to acute stressors. In addition, acute stress affected significantly brain mRNA expression levels of several genes (corticotropin-releasing factor, crf; pro-opiomelanocortin, pomc; glucocorticoid receptor, gr; MR/GR ratio; prolactin, prl; hypocretin/orexin, hcrt; brain-derived neurotrophic factor, bdnf; c-fos). Exposure of fish to unpredictable relatively low-grade environmental and husbandry stressors (SP-1) did not affect the overall behaviour of fish, as well as trunk cortisol concentrations. Fish exposed to relatively higher-grade long-term stressors (SP-2) showed elevated cortisol levels as well as significant changes in most of gene transcripts. In particular, fish exposed to SP-2 showed statistically significant upregulation in brain gr, mr, prl and hcrt compared to SP-1 and control individuals. The highest mean values of bdnf transcripts were found in SP-2 exposed zebrafish and the lowest in control fish, while an approximately 5 to 6-fold upregulation was observed in c-fos mean relative mRNA levels of long-term stress-exposed fish, regardless of stressor intensity, compared to control zebrafish. In conclusion, we developed realistic acute and unpredictable long-term stress protocols, based on husbandry and environmental stressors and physical, chemical, mechanical and social stimuli that fish may experience either in nature or under intensive rearing conditions.
Copyright © 2015Elsevier, Inc.
