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See detailPolychlorinated Biphenyls affect Histological Appearance of European sea bass (Dicentrarchus labrax) Thyroids
Schnitzler, Joseph ULg; Klaren, Peter; Celis, Niko et al

Conference (2010)

Polychlorobiphenyls (PCBs) are well-described endocrine disrupters and of particular interest are effects on thyroid function. We propose here a thorough approach to assess effects of these compounds on ... [more ▼]

Polychlorobiphenyls (PCBs) are well-described endocrine disrupters and of particular interest are effects on thyroid function. We propose here a thorough approach to assess effects of these compounds on the thyroid function of European sea bass (Dicentrarchus labrax). An experimental exposure of sea bass to commercial PCB mixtures has been designed to understand underlying toxicity mechanisms and effects on the thyroid system. After 120 days of exposure histological appearance of thyroid tissue was assessed by light and electron microscopy. The follicle area, perimeter, diameter, length and with of every follicle cross section were interactively measured. The shape of the follicles was described with three dimensionless shape descriptors: roundness, form factor and aspect ratio. The histomorphometrical analysis showed a greater heterogeneity of thyroid follicle diameter and especially higher epithelial cell heights in sea bass exposed to environmental relevant doses of PCB (from 0.3 to 0.9 μg g-1 [7 ICES PCB]). Ultrastructural histological investigations showed that the epithelial cells surrounding the bigger follicles present an higher accumulation of colloid droplets. This was interpreted to be the result of increased stimulation of follicular cells. No differences in shape could be identified among the different treatment groups The size of the follicles and the form of the follicular cells gives an indication of the secretary activity of the gland. These observations support the hypothesis that the contamination of PCB mixtures can induce a hyperactivity of the thyroid tissue. These observations were confirmed by measurements of muscular thyroid hormone concentrations and activity thyroid hormone metabolism. [less ▲]

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See detailEffects of Polychlorinated Biphenyls on Thyroid Hormone Physiology and Metabolism of European sea bass (Dicentrarchus labrax)
Schnitzler, Joseph ULg; Klaren, Peter; Celis, Niko et al

Conference (2010)

Studies in the laboratory have shown that a number of synthetic and natural chemicals can interfere with the endocrine system in fish. Among them, organic compounds such as pesticides and ... [more ▼]

Studies in the laboratory have shown that a number of synthetic and natural chemicals can interfere with the endocrine system in fish. Among them, organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters. Of particular interest are effects on thyroid function, but data on effects of PCB exposure on these hormones and related metabolism has been lacking. We propose here a thorough approach to assess effects of these compounds on the thyroid function of European sea bass (Dicentrarchus labrax). An experimental exposure of sea bass to commercial PCB mixtures has been designed to understand underlying toxicity mechanisms and effects on the thyroid system. After 120 days of exposure, muscular thyroid hormone concentrations and the main metabolic pathways for thyroid hormones (deiodination, glucuronidation and sulfatation) were assessed. Exposure to environmental relevant doses of PCB (from 0.3 to 0.9 ppm [7 ICES PCB]). alters hepatic T4 outer ring deiodinase and T4 sulfatation whereas T4 glucuronidation was not affected. Owing to the extensive autoregulatory feedback at both central and peripheral levels, the thyroid hormone concentrations were preserved despite the PCB induced changes in thyroid hormone dynamics. At 10 times higher concentrations (10 ppm [7 ICES PCB]). an important depression of muscular T3 and T4 levels could be observed which are apparently caused by other mechanisms than metabolic pathways. Further analysis is required to evaluate thyroid gland function and secretion. These results support the observations made in our field study in wild sea bass (Dicentrarchus labrax) from coastal regions near several important European rivers mouths. [less ▲]

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See detailApproaches for assessing potential impacts of thyroid hormone disrupting chemicals in wild sea bass (Dicentrarchus labrax)
Schnitzler, Joseph ULg; Klaren, Peter; Thomé, Jean-Pierre ULg et al

Poster (2010)

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring ... [more ▼]

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring pollutants in European coastal areas to disrupt the thyroid system in sea bass, a field study in the major European estuaries, namely, the Scheldt, the Seine, the Loire, the Charente and the Garonne has been conducted. Several thyroid endpoints were simultaneously examined. Diameter of follicles and the epithelial cell heights give an indication on the production and secretion activity of the thyroid gland. The activity of enzymes involved in the metabolism (deiodination, glucuronidation and sulfatation) of thyroid hormones was analyzed. Finally thyroxine (T4) and triiodothyronine (T3) concentrations were analyzed in muscle by radioimmunoassay. The combined use of all those endpoints gives us an overview of the complex thyroid hormone system. PCB concentration in wild fish varied from 10 to 100 ng g-1 wet weight (ww) depending on length and location. Each region has its own contamination levels and profiles reflecting the contribution of pollutants from rivers. The contamination levels were as follows: the highest concentrations were measured in individuals collected from the coastal region near the Scheldt > Seine > Loire > Charente and the lowest levels were observed in sea bass from coastal regions near the Garonne. Measurements of metabolic activity revealed an altered hepatic T4 outer ring deiodinase whereas T4 sulfatation and T4 glucuronidation were not affected. Owing to the extensive autoregulatory feedback at both central and peripheral levels, the thyroid hormone concentrations were preserved despite the PCB induced changes in thyroid hormone dynamics. [less ▲]

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See detailPersistent organic pollutants in wild seabass (Dicentrarchus labrax) from the Northeast atlantic coastal regions and relationship with thyroid hormone levels
Schnitzler, Joseph ULg; Thomé, Jean-Pierre ULg; Das, Krishna ULg

Poster (2008, October 30)

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), Aldrin and Dieldrin were analysed in the muscle of sea bass ... [more ▼]

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), Aldrin and Dieldrin were analysed in the muscle of sea bass (Dicentrarchus labrax) sampled in coastal regions near several important European river mouths (Garonne, Charente, Loire, Seine and Scheldt). These organochlorinated compounds are known to influence the endocrine system of many fish species and mammals and are thus qualified as endocrine disrupters. To highlight a potentially harmful effect of these compounds on the thyroid function of these fishes, we measured the muscular concentrations of thyroid hormones T3 and T4 by Radio-Immuno-Assay. The contamination levels were as follows: the highest concentrations were measured in individuals collected from the coastal region near the Scheldt > Seine > Loire > Charente and the lowest levels were observed in sea bass from coastal regions near the Garonne (from 2422 to 6188 ng.g-1 lw). The measured levels were generally higher than those reported in literature in sea bass from other regions in the Mediterranean Sea. Contamination patterns were different depending on the sampling area and thus the river input of pollutants. The multivariate statistical analysis revealed a significant relationship between the measured persistent organic pollutants and thyroid hormones in muscle. We cannot exclude the assumption that an endocrine disruption of the thyroid related to these pollutants could be the origin of these modifications of the thyroid hormone concentrations. [less ▲]

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See detailHarbour porpoise thyroids: Histological investigations and potential interactions with environmental factors
Schnitzler, Joseph ULg; Siebert, Ursula; Jepson, Paul et al

in Journal of Wildlife Diseases (2008), 44

The thyroid plays an important role in development and is of primary importance in metabolism and heat loss for cetaceans, including the harbor porpoise (Phocoena phocoena). Several studies have ... [more ▼]

The thyroid plays an important role in development and is of primary importance in metabolism and heat loss for cetaceans, including the harbor porpoise (Phocoena phocoena). Several studies have demonstrated that environmental contaminants can alter various aspects of thyroid function in mammals and may contribute to various histologic changes. The present study completes the data set of a 2006 study by Das et al., by performing histological and immunohistologic investigations on thyroids of 36 harbor porpoises from Belgian and United Kingdom waters. The number and mean diameter of follicles (µm) and the relative proportion of follicular, connective, and vascular tissue (%) were quantified in the thyroid gland of each individual. Interfollicular fibrosis has been observed in these thyroid glands, and the collective findings support the hypothesis of an endocrine disruption of thyroid function through organochlorinated compounds. Our study aimed also to reveal potential relationships between thyroid morphometric data and metal levels (Cd, Fe, Zn, Cu, Se, and Hg) using multivariate statistical analysis. The multiple regressions revealed statistically significant relationships between trace elements (cadmium, selenium, and copper) and thyroid fibrosis. The largely negative relationships are interesting findings but do not support the hypothesis that these elements have an adverse effect on thyroid morphometry. Further research is needed to understand the nature of any relationship between organochlorine and trace element exposure and thyroid gland morphology and function in harbor porpoises. [less ▲]

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See detailEffects of persistent organic pollutants on the thyroid function of the European sea bass (Dicentrarchus labrax) from the Aegean Sea, is it an endocrine disruption?
Schnitzler, Joseph ULg; Koutrarkis, Emmanuil; Siebert, Ursula et al

in Marine Pollution Bulletin (2008), 56(10), 1755-1764

We evaluated the alterations of organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) on the thyroid in wild ... [more ▼]

We evaluated the alterations of organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) on the thyroid in wild and cultured sea bass (Dicentrarchus labrax) at environmental concentrations. These compounds influence the endocrine system of many fish species and are qualified as endocrine disruptors. The thyroid seems to be a target organ. Two alteration endpoints: the thyroid histology and the muscular thyroid hormone concentrations, were used simultaneously. High concentrations in PCBs and DDT were detected in muscles, supporting the idea that the Mediterranean fauna could be more polluted than the Atlantic fauna. The high abundance of DDE indicates a progressive degradation of remnant DDT load and the absence of new inputs in this area. Aquaculture sea bass shows a significant higher amount of pollutants on fresh weight basis (especially PCBs) in their muscles compared to the wild sea bass. Those differences may be related mainly to the contaminations of diet. Thyroid parameters vary between wild and aquaculture sea bass, wild sea bass were characterized by higher follicle diameters, epithelial cell heights and muscular T4 concentrations. A significant relationship between persistent organic pollutants (muscular PCBs and DDT concentration) and the different thyroid parameters (diameters of follicles, epithelial cell heights and muscular T4 levels) could be observed, which support the hypothesis that these compounds have an adverse impact on thyroid morphometry and function. [less ▲]

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See detailHarbour porpoises stranded on the Dutch coast in 2007: Impact of by cath and related lesions
Grondin, Alexia; Camphuysen, K.; Ghisbain, T. et al

Poster (2008)

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See detailCauses of death of harbor porpoises (Phocoena phocoena) stranded on the Dutch coast
Jauniaux, Thierry ULg; Bergerie, H.; Camphuysen, K. et al

in proceeding of the annual conference (2008)

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See detailEffects of persistent organic pollutants on the thyroid function of the sea bass (Dicentrarchus labrax), an endocrine disruption?
Schnitzler, Joseph ULg; Koutrakis, Emmanuil; Thomé, Jean-Pierre ULg et al

Conference (2007, May 23)

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine ... [more ▼]

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine system of many fish species and mammals and are thus qualified as endocrine disruptors. The objective of this project aims a better understanding of the effects of these compounds on the thyroid function of European seabass (Dicentrarchus labrax). Thyroid tissue and muscle of 46 seabass from the Aegean Sea in Greece (fished and aquaculture, n=15 and n=31, respectively) were sampled. The levels in PCBs, DDT and DDE were evaluated in the muscles of 30 individuals. The diameter of follicles and the epithelial cell heights were measured in each individual by optical microscopy. The concentration of the thyroid hormone T4 (thyroxin) was measured by Radio-Immuno-Assay (RIA). Finally, the potential relationships between these thyroid parameters and these organic compounds were investigated using factor analysis and multiple regressions. A significant relationship between persistent organic pollutants (muscular PCBs and DDT concentration) and the different thyroid parameters (diameters of follicles, epithelial cell heights and muscular T4 levels) could be observed. We cannot exclude the assumption that an endocrine disruption of thyroid gland related to these pollutants could be the origin of the modifications of these thyroid parameters. [less ▲]

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See detailLesions observed on harbor porpoises (Phocoena phocoena) stranded on the Dutch coast in 2006
Jauniaux, Thierry ULg; Bergerie, H.; Camphuysen, K. et al

(2007)

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See detailStudy of endocrine disruption in seabass (Dicentrarchus labrax)
Schnitzler, Joseph ULg; Koutrakis, Emmanuil; Thomé, Jean-Pierre ULg et al

Conference (2006, October 28)

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine ... [more ▼]

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine system of many fish species and mammals and are thus qualified as endocrine disruptors. The objective of this project aims a better understanding of the effects of these compounds on the thyroid function of European seabass (Dicentrarchus labrax). Thyroid tissue and muscle of 46 seabass from the Aegean Sea in Greece (fished and aquaculture, n=15 and n=31, respectively) were sampled. The levels in PCBs, DDT and DDE were evaluated in the muscles of 30 individuals. The diameter of follicles and the epithelial cell heights were measured in each individual by optical microscopy. The concentration of the thyroid hormone T4 (thyroxin) was measured by Radio-Immuno-Assay (RIA). Finally, the potential relationships between these thyroid parameters and these organic compounds were investigated using factor analysis and multiple regressions. A significant relationship between persistent organic pollutants (muscular PCBs and DDT concentration) and the different thyroid parameters (diameters of follicles, epithelial cell heights and muscular T4 levels) could be observed. We cannot exclude the assumption that an endocrine disruption of thyroid gland related to these pollutants could be the origin of the modifications of these thyroid parameters. [less ▲]

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See detailInterfollicular fibrosis and organohalogens in the thyroid of the harbour porpoise (phocoena phocoena) of the British and Belgian coasts
Schnitzler, Joseph ULg; Das, Krishna ULg; Beineke, Andreas et al

Conference (2005, October 27)

Previous studies have described high levels of polychlorobiphenyls (PCB), p,p`-dichlordiphenyl-dichlorethen (DDT), p,p`-dichlordiphenyl-trichlorethan (DDE) and polybrominated diphenylether (PBDE) in the ... [more ▼]

Previous studies have described high levels of polychlorobiphenyls (PCB), p,p`-dichlordiphenyl-dichlorethen (DDT), p,p`-dichlordiphenyl-trichlorethan (DDE) and polybrominated diphenylether (PBDE) in the blubber of the harbour porpoise (Phocoena phocoena) from the North Sea raising the question of a potential endocrine disruption in this species. In the present study, the thyroids of 36 harbour porpoises from the British and the Belgian coast have been collected for histological and immunohistological investigations. The number and mean diameter of follicles and the relative distribution of follicular, connective and vascular tissues (%) were quantified in the thyroid of each individual. Then, the relationship between the thyroid morphometry data and previously described organic compounds (namely PCB, DDT, DDE and PBDE) was investigated using factor analysis and multiple regressions. The results of this work were compared to the previous study of harbour porpoises from the German (North and Baltic Seas), Norwegian and Icelandic coasts. Thyroid morphology was similar between the harbour porpoises from the British and Belgian coast. Compared to the previous study, the thyroids differed strongly between sampling sites. Porpoises from the German (North and Baltic Seas) and Norwegian coasts displayed a high percentage of connective tissues between 30 and 38% revealing severe inter-follicular fibrosis. The thyroids of Icelandic coasts displayed only a light inter-follicular fibrosis (percentage of connective tissue of 3%). The thyroids of the porpoises from the British and Belgian coasts occupied an intermediary place with a moderate fibrosis (percentage of connective tissue of 10%). A relation between mean diameter of follicles and the body size and mass suggesting a downward trend of activity of the thyroid with increasing body size and mass and thus, the age of the porpoises. A correlation-based principal component analysis (PCA) revealed one principal components explaining 69% of the total variance. The variables PCB, PBDE, DDT, and DDE compounds loaded highest on PC1. Our results pointed out a relationship between PCBs, PBDE, DDE and DDT (PC1) compounds and interfollicular fibrosis in the thyroids of harbour porpoises from the German coast of the Baltic Sea. The present report supports the hypothesis of a contaminant-induced thyroid fibrosis in harbour porpoises raising the question of the long term-viability in highly polluted areas [less ▲]

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See detailEtude histomorphométrique de la glande thyroïde du marsouin commun (Phocoena phocoena) (L.): Relation potentielle avec différents organohalogénés
Schnitzler, Joseph ULg

Master's dissertation (2005)

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine ... [more ▼]

Organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) have the characteristic to influence the endocrine system of many fish species and mammals and are thus qualified as endocrine disruptors. The objective of this project aims a better understanding of the effects of these compounds on the thyroid function of European seabass (Dicentrarchus labrax). Thyroid tissue and muscle of 46 seabass from the Aegean Sea in Greece (fished and aquaculture, n=15 and n=31, respectively) were sampled. The levels in PCBs, DDT and DDE were evaluated in the muscles of 30 individuals. The diameter of follicles and the epithelial cell heights were measured in each individual by optical microscopy. The concentration of the thyroid hormone T4 (thyroxin) was measured by Radio-Immuno-Assay (RIA). Finally, the potential relationships between these thyroid parameters and these organic compounds were investigated using factor analysis and multiple regressions. A significant relationship between persistent organic pollutants (muscular PCBs and DDT concentration) and the different thyroid parameters (diameters of follicles, epithelial cell heights and muscular T4 levels) could be observed. We cannot exclude the assumption that an endocrine disruption of thyroid gland related to these pollutants could be the origin of the modifications of these thyroid parameters. [less ▲]

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