Altered stress responses in rainbow trout following a dietary administration of cortisol and β-napthoflavone |
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| Authors: | N Basu CJ Kennedy PV Hodson GK Iwama |
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| Institution: | (1) Faculty of Agricultural Sciences and AquaNet, University of British Columbia, Vancouver, Canada;(2) Present address: Biotechnology Research Institute, National Reserach Council of Canada, Montreal, Canada;(3) Department of Biological Sciences, Simon Fraser University, Burnaby, Canada;(4) School of Environmental Studies, Queen's University, Kingston, Canada |
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| Abstract: | Previous studies have demonstrated that fish inhabiting polluted waterways often have an impaired stress response at the organismal
level. Given the possible link between the organismal (i.e. cortisol) and cellular (i.e. heat shock proteins; hsp) stress
responses, we conducted this study to examine the ability of rainbow trout to respond to a 2 h, +14 °C heat stress (HS) challenge
following a 28 d, sub-chronic exposure to increased concentrations of cortisol (5 mg kg−1 b.w.), β-napthoflavone (bnf; 50 mg kg−1 b.w.), and a combination of both (mixture), through the diet (1.5% b.w. every 48 h). While control fish responded to the
HS by significantly increasing components of their organismal (cortisol, glucose, and lactate) and cellular (hepatic hsp70
protein) stress responses 6 and 24 h post HS, cortisol-, bnf-, and mixture-fed fish had impaired stress responses at both
levels of organization. Additionally, hepatic hsp70 levels were significantly reduced 6 h post HS in cortisol-fed fish. While
bnf-fed fish had significantly higher EROD activity, cortisol potentiated EROD activity in the mixture-fed fish. Similarly,
plasma cortisol concentrations in the mixture-fed fish were significantly lower relative to cortisol-fed fish. These data
are the first to indicate that sub-chronically stressed fish can have impaired stress responses at both the organismal and
cellular levels. These findings raise questions regarding: (a) the universal and simple applicability of biological indicators
of stress in fish; (b) the possible functional relationship between these two levels of stress responses; and (c) the importance
of hsps in the generalized stress response of the whole organism.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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| Keywords: | fish generalized stress response glucose heat shock proteins hsp70 lactate polycyclic aromatic hydrocarbons toxicants |
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