Changes in the immune system of Atlantic salmon (Salmo salar) exposed to long-term stress

• Main Authors: Fast, M. D., Sho, H., Afonso, L. O.B., Johnson, S. C.
• Format: Other/Unknown Material
• Language: English
• Subjects: Atlantic salmon; Salmo salar; stress
• Online Access: https://nrc-publications.canada.ca/eng/view/object/?id=1d40024e-c59a-4375-87be-aea5938de2ba; https://nrc-publications.canada.ca/fra/voir/objet/?id=1d40024e-c59a-4375-87be-aea5938de2ba

It is generally considered that long term stress causes decreased immune function in fish. In this study we examined the effects of 4 weeks of daily handling stress (15 seconds out of water) on plasma cortisol (free and total) and glucose levels, liver HSP70 levels, expression of interleukin 1 β (IL-1β) and killing of head kidney macrophages by Aeromonas salmonicida. Samples were collected weekly prior to the application of the daily stress. With the exception of an increase in plasma glucose levels at 1 week there were no significant differences in plasma parameters of HSP70 levels. There was a significantly higher unstimulated IL-1β expression in stressed fish over the first two weeks. Prior to stress and at 3 and 4 weeks unstimulated IL-1β expression levels were not different from the controls. At weeks 1, 2 and 3 the magnitude of IL-1β response of isolated head kidney macrophages to lipopolysaccharide (LPS) stimulation was reduced in >90% of the stressed fish. At 4 weeks there was no significant difference in inducible IL-1β expression between the groups. Macrophages isolated from stressed fish showed significantly decreased survival when exposed to A. salmonicida. The implications of these changes in the immune system will be discussed with respect to the use of classical indicators of stress to predict possible effects on the immune system of fish. This work was funded by NRC Genomics and Health Initiative. Peer reviewed: No NRC publication: Yes