Stress in XXXX : response to unpredictable chronic stress.

@entity12178 @entity701 @entity10076
UNASSIGNED: Combinations of stressors occur regularly throughout an animal's life, especially in agriculture and aquaculture settings. If an animal fails to acclimate to these stressors, stress becomes chronic, and a condition of allostatic overload arises with negative results for animal welfare. In the current study we describe effects of exposing @entity12178 parr to the unpredictable chronic stressor (UCS) paradigm for three weeks. The paradigm involves exposure of fish to 7 unpredictable stressors three times a day. At the end of the trial, experimental and control fish were challenged with yet another novel stressor and sampled before and 1   h after that challenge. Plasma @entity701 decreased steadily over time in stressed fish, indicative of exhaustion of the endocrine stress axis. This was confirmed by a lower @entity701 response to the novel stressor at the end of the stress period in chronically stressed fish compared to the control group. In the preoptic area (POA) and pituitary gland, chronic stress resulted in decreased gene expression of 11bhsd2, gr1 and gr2 in POA and increased expression of those genes in the pituitary gland. POA crf expression and pituitary expression of pomcs and mr increased, whereas interrenal gene expression was unaffected. Exposure to the novel stressor had no effect on POA and interrenal gene expression. In the pituitary, crfr1, pomcs, 11bhsd2, grs and mr were down-regulated. In summary, our results provide a novel overview of the dynamic changes that occur at every level of the @entity10076 as a result of chronic stress in @entity12178 .
