Elevated plasma cortisol induces organ-specific changes in glucocorticoid receptor expression and in the innate immune response in Sparus aurata
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1
Universitat Autònoma de Barcelona, Department of Cell Biology, Physiology and Immunology, Spain
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2
Aveiro University, CESAM & Biology Department, Portugal
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3
Generalitat de Catalunya, Xarxa de Referència en Recerca i Desenvolupament en Aqüicultura, Spain
Cortisol controls a wide variety of biological responses, such as intermediary metabolism, osmoregulation and immune functions. Its action involves the activation of specific intracellular receptors - the glucocorticoid receptors (GR) - that have been previously described in different fish species including the teleost Sparus aurata (gilthead seabream).
The present work was designed to assess the effects of high plasma cortisol levels induced by slow-release cortisol implants in the mRNA transcription of the GR in head kidney, spleen, gills and intestine of the gilthead seabream. For that purpose fish were intraperitoneally injected with the implants containing two different concentrations of cortisol (50 or 200 µg/g body weight) to simulate a cortisol secretion after chronic stress, and blood and organs sampled after 7 and 14 days of implantation. Only fish with 200 µg/g implants exhibited a significant rise in the plasma cortisol.
On the basis of these results, we evaluated the expression of the GR in the previously mentioned organs of the gilthead seabream injected with 200 µg/g cortisol implants. GR gene expression was up-regulated in head kidney after 7 and 14 days of cortisol implantation, as well as on gills 7 days after cortisol implantation. On the other hand, GR expression was significantly decreased in intestine 14 days after cortisol implantation and unchanged in spleen.
These results suggest that increased plasma cortisol induced by a slow-release implant of cortisol mimics the effects of chronic stress and affects the expression of GR in a time and organ-specific manner.
Additionally, we determined the effects of high plasma cortisol levels in the haemolytic activity of plasma (complement activity), as a non-specific defence mechanism in teleosts. However, while plasma cortisol levels were generally increased, the tendency of plasma complement was opposite, showing a significant decrease after 14 days implantation with 50 or 200 µg/g body weigh cortisol. These results suggest that high plasma cortisol affects the innate immune response of gilthead seabream and may increase its susceptibility to disease.
Keywords:
comparative endocrinology
Conference:
25th Conference of the European Comparative Endocrinologists, Pécs, Hungary, 31 Aug - 4 Sep, 2010.
Presentation Type:
Conference Presentation
Topic:
Comparative endocrinology
Citation:
Teles
M,
Mackenzie
S,
Boltaña
S,
Pacheco
M,
Santos
MA and
Tort
L
(2010). Elevated plasma cortisol induces organ-specific changes in glucocorticoid receptor expression and in the innate immune response in Sparus aurata .
Front. Endocrinol.
Conference Abstract:
25th Conference of the European Comparative Endocrinologists.
doi: 10.3389/conf.fendo.2010.01.00043
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Received:
26 Aug 2010;
Published Online:
29 Aug 2010.
*
Correspondence:
Dr. Mariana Teles, Universitat Autònoma de Barcelona, Department of Cell Biology, Physiology and Immunology, Barcelona, Spain, mteles@ua.pt