Repeated acute stress reduces growth rate of Atlantic salmon parr and alters plasma levels of growth hormone, insulin-like growth factor I and cortisol (original) (raw)
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Journal of Experimental Biology
Stress and elevated plasma cortisol in salmonids have been linked with pathological remodeling of the heart and deterioration of fitness and welfare. However, these associations were based on biomarkers that fail to provide a retrospective view of stress. This study is the first whereby the association of long-term stress, using scale cortisol as chronic stress biomarker, with cardiac morphology and growth performance of wild Atlantic salmon (Salmo salar) is made. Growth, heart morphology, plasma and scale cortisol levels, and expression of genes involved in cortisol regulation of the hypothalamic-pituitary-interrenal axis of undisturbed fish (CONTROL) were compared with fish exposed daily to stress (STRESS) for 8 weeks. Though scale cortisol levels showed a time-dependent accumulation in both groups, plasma and scale cortisol levels of STRESS fish were 29.1% and 25.0% lower than CONTROL, respectively. These results correlated with the overall upregulation of stress-axis genes invol...
Stress in Atlantic salmon: response to unpredictable chronic stress
Journal of Experimental Biology, 2015
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 Atlantic salmon parr to an unpredictable chronic stressor (UCS) paradigm for 3 weeks. The paradigm involves exposure of fish to seven 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 cortisol decreased steadily over time in stressed fish, indicative of exhaustion of the endocrine stress axis. This was confirmed by a lower cortisol response to the novel stressor at the end of the stress period in chronically stressed fish compared with the control group. In the preoptic area (POA) and pituitary gland, chronic stress resulted in decreased gene expression of 11βhsd2, gr1 and gr2 in the 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, 11βhsd2, grs and mr were downregulated. In summary, our results provide a novel overview of the dynamic changes that occur at every level of the hypothalamicpituitary gland-interrenal gland (HPI) axis as a result of chronic stress in Atlantic salmon.
Acute Physiological Stress Down-Regulates mRNA Expressions of Growth-Related Genes in Coho Salmon
PLoS ONE, 2013
Growth and development in fish are regulated to a major extent by growth-related factors, such as liver-derived insulin-like growth factor (IGF)-1 in response to pituitary-secreted growth hormone (GH) binding to the GH receptor (GHR). Here, we report on the changes in the expressions of gh, ghr, and igf1 genes and the circulating levels of GH and IGF-1 proteins in juvenile coho salmon (Oncorhynchus kisutch) in response to handling as an acute physiological stressor. Plasma GH levels were not significantly different between stressed fish and prestressed control. Plasma IGF-1 concentrations in stressed fish 1.5 h post-stress were the same as in control fish, but levels in stressed fish decreased significantly 16 h post-stress. Realtime quantitative PCR (qPCR) analysis showed that ghr mRNA levels in pituitary, liver, and muscle decreased gradually in response to the stressor. After exposure to stress, hepatic igf1 expression transiently increased, whereas levels decreased 16 h post-stress. On the other hand, the pituitary gh mRNA level did not change in response to the stressor. These observations indicate that expression of gh, ghr, and igf1 responded differently to stress. Our results show that acute physiological stress can mainly down-regulate the expressions of growth-related genes in coho salmon in vivo. This study also suggests that a relationship between the neuroendocrine stress response and growth-related factors exists in fish.
Stress hormones and the cellular stress response in salmonids
Fish Physiology and Biochemistry, 2000
The relationship between stress protein (SP) levels and the hormonal stress response in salmonids was examined through the measurement of gill SP70 and SP30 levels together with plasma cortisol, glucose and ion concentrations, in response to handling stress (45 s holding in a net), intraperitoneal cortisol implants, and heat shock (+10 °C). Handling and cortisol implants resulted in increased plasma cortisol and