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Identifier 000376378
Title Μεταβολικές επιπτώσεις τησ οξείας καταπόνησης στο λαβράκι, Dicentrarchus labrax, και στο κρανίο, Argyrosomus regius, σε διαφορετικές εποχές και δοκιμασία καταστολής της κορτιζόλης με δεξαμεθαζόνη στο λαβράκι / Σαμαράς Αθανάσιος.
Alternative Title Metabolic effects of acute stess in European sea bass, Dicentrarchus labrax, and meagre, Argyrosomus regius, in different season and dexamethasone suppresion test in European sea bass
Author Σαμαράς, Αθανάσιος
Thesis advisor Παυλίδης, Μιχάλης
Abstract The stress response in fish varies between different species, as well as between different environmental conditions within the same species. In this context, the stress response of two teleost species, European sea bass, Dicentrarchus labrax, and meagre, Argyrosomus regius, species that share some common ecological features, such as tolerance to changes in salinity, temperature and oxygen levels, but differ in the baseline and peak plasma values of some commonly used stress indicators, such as cortisol, glucose and lactate concentration. The working hypothesis was that the observed differences were related to metabolic discrepancies between these two species. Fish reared in net pen sea cages were used, with samplings taking place in three different seasons, with different sea temperature and differences in the physiological condition of the fish. Furthermore, a study of the kinetics of the stress response was conducted in these two species, focusing in the changes in the glycogen concentration of liver and muscle and the alterations of blood and muscle pH levels. Moreover, since sea bass shows high baseline concentrations of cortisol, as well as intense stress response, the study of the functionality of the Hypothalamus- Pituitary-Interrenal (HPI) axis was conducted via the dexamethasone suppression test, which is widely used in mammals for research and diagnostic reasons. The results showed that sea bass had higher carbohydrate energy reserves than meagre, as well as higher capacity for oxygen transport to the tissues. It also utilized the anaerobic metabolism in a higher degree. Furthermore, sea bass had higher cortisol concentration than meagre, both in control and stress fish, and in every environmental temperature. Between the different temperatures the pattern of the stress response was the same for some of the studied hematological and biochemical features, while it differed in some other.Dexamethasone suppressed cortisol levels to 25%-50% of the initial concentration, depending on the dose, 24 h after the injection. In contrast, it wasn’t able to suppress cortisol 4 h after the injection, probably due to the already increased, by the handling, levels of the hormone. Dexamethasone also led to a slight hyperglycemia, as well as blood alkalosis and decreased levels of haematocrit.
Language Greek
Subject Ιχθύες
Issue date 2012-11-16
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/6/3/4/metadata-dlib-1353499272-28312-587.tkl Bookmark and Share
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