β-Naphthoflavone disrupts cortisol production and liver glucocorticoid responsiveness in rainbow trout
In: Aquatic Toxicology. Elsevier Science: Tokyo; New York; London; Amsterdam. ISSN 0166-445X; e-ISSN 1879-1514, more
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| Keywords |
Fauna > Aquatic organisms > Aquatic animals > Fish
Metabolism > Lipid metabolism > Steroid metabolism > Steroidogenesis
Stress
Stress
Stress-strain relations
Oncorhynchus mykiss (Walbaum, 1792) [WoRMS]
Marine/Coastal; Brackish water; Fresh water |
| Author keywords |
aryl hydrocarbon receptor; Oncorhynchus mykiss; CYP1A; steroidogenesis;glucocorticoid receptor; alpha-naphthoflavone; fish; stress |
| Authors | | Top |
- Aluru, N.
- Vijayan, M.M., correspondent
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| Abstract |
We investigated the impact of aryl hydrocarbon receptor (AhR) activation on cortisol production in rainbow trout (Oncorhynchus mykiss) using -naphthoflavone (BNF) and a-naphthoflavone (ANF) as agonist and antagonist of AhR, respectively. Fish were given a single intraperitoneal injection of either corn oil alone or corn oil containing ANF (50 mg/kg body mass), BNF (50 mg/kg) or a combination of both (ANF/BNF; 50 mg/kg each) and sampled at 2- and 6-day post-injection. Higher CYP1A protein expression in the liver and mRNA abundance in the head kidney confirmed AhR activation with BNF, but ANF did not abolish this response. BNF treatment did not significantly affect mRNA abundance of key steroidogenic enzymes (StAR protein, P450 side chain cleavage and 11β-hydroxylase) in the head kidney of trout. However, BNF depressed the in vitro ACTH- or 8-br-cAMP-mediated cortisol production and this effect was also not modified by ANF. Plasma cortisol levels were significantly higher with BNF in the present study and this BNF-mediated cortisol response was completely abolished with ANF suggesting a role for AhR and/or CYP1A in the regulation of plasma cortisol concentration. However, despite elevated plasma cortisol levels, there was no significant effect of BNF on liver glucocorticoid receptor (GR) protein expression suggesting a lack of liver responsiveness to cortisol stimulation. Also, this was reflected in the absence of any change in plasma glucose concentration in the BNF group at 2 days, and a significant drop at 6 days compared to other treatments. Altogether, our results suggest that AhR activation disrupts interrenal corticosteroidogenesis and target tissue responsiveness to glucocorticoid stimulation in rainbow trout. |
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