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The aim of the present study is to determine if Ahr ligands as PCB-126, a dioxin-like, might contribute to inhibition of the tumour suppressor p53 by promoting its degradation through proteasome-ubiquitin system (UPS). The findings show, in the presence of PCB-126, a significant increase in p53 immunoreactivity in fish compared to the control. Subsequently, there is a decrease in p53 immunoreactivity at 24 h which is maintained even at 72 h. There is also a slight decrease in ubiquitin immunoreactivity to 12 h compared to the control and a marked decrease to 24 and 72 h. It's very important to underline as in this study we demonstrate a marked decrease in ubiquitin and p53 immunoreactivity at 24 and 72 h. Our result emphasise the need to deeply the role of this receptor in UPS regulation as potential therapeutic target for cancer treatment.

The aryl hydrocarbon receptor (AHR) mediates a variety of biological responses to ubiquitous dioxin and PCB dioxin-like. AHR together with ARNT, AHRR, represent a novel basic helix-loop-helix/PAS family of transcriptional regulators. Their interplay may affect the xenobiotic response. The aim of this study was to investigate, by histological, immunohistochemical investigations and western-blot analysis, the expression of AHR, ARNT and AHRR in liver of seabrem (Spaurus aurata) after exposure at different time to dioxin-like PCB126 in order to deep the knowledge about their specific role. The findings showed a significant increase of AHR and ARNT expression in juvenile fishes after 12 h than control group. The induction of AHR and ARNT is also significant at 24 and 72 hours compared to the control group. Furthemore, induction of AHRR expression has proved to increase both 12 h but this induction does not seem significant to 24 and 72 hours. The most important data of this work is that the induction of AHRR, when the action of the toxic persistence substances, as dioxin and PCB-126, it is not enough to reduce AHR signaling and thus its hyperactivation leads to toxic effects in seabrem (Spaurus aurata). All this confirms the importance of AHR ligands as new class of drugs that can be directed against severe disease such as cancer.

The effects of polychlorinated biphenyl congeners 126 and 153 (PCB-126 and PCB-153) on vitellogenin (Vtg) and cytochrome (CYP1A1) expression were evaluated in 60 juvenile Sparus aurata. Fish were divided into four groups and the control group (Group A) was compared to fish exposed to PCB-126 (10-8M) (Group B), PCB-153 (10-6M) (Group C) singly and also in combination (Group D) for 12, 24 and 72 h. Hepatic expression of Vtg and CYP1A1 were analyzed using histological examinations and by immunochemical (Western blotting and immunohistochemistry) methods. Vtg increased in juvenile fishes of Groups B, C and D after 12h respect to Group A and decreased after 24 and 72 h respect to 12h in each group. CYP1A1 increased after 12 and 24h in all groups vs control group and increased in Group B only at 72 h vs in control group. The results showed that chemical interaction and endocrine disruption in fish might produce deleterious consequences not only for fish but also for human., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The presence of mast cells has been reported in all classes of vertebrates, including many teleost fish families. The mast cells of teleosts, both morphologically and functionally, show a close similarity to the mast cells of mammals. Mast cells of teleosts, localized in the vicinity of blood vessels of the intestine, gills and skin, may play an important role in the mechanisms of inflammatory response, because they express a number of functional proteins, including piscidins, which are antimicrobical peptides that act against a broad-spectrum of pathogens. An increase in the number of mast cells in various tissues and organs of teleosts seems to be linked to a wide range of stressful conditions, such as exposure to heavy metals (cadmium, copper, lead and mercury), exposure to herbicides and parasitic infections. This study analyzed the morphological localization and abundance of mast cells in the intestine and gills of sea bream, Sparus aurata, after a 12, 24 or 72 h exposure to PCB 126, a polychlorinated biphenyl, which is a potent immunotoxic agent. In the organs of fish exposed to PCB 126, it was observed that in addition to congestion of blood vessels, there was extravasation of red blood cells, infiltration of lymphocytes, and a progressive increase in numbers of mast cells. These data confirm the immunotoxic action of PCB, and the involvement of mast cells in the inflammatory response., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Vitellogenin (Vtg) is a phospho-lipo-glycoprotein produced by oviparous animals in response to estrogen receptor (ER) binding. The presence of Vtg in juvenile and male fish liver and plasma has been used as biomarker to evaluate levels of environmental contaminants as dioxin and PCBs. Interaction of dioxins and PCBs with aryl hydrocarbon receptor (AhR) may affect reproduction by recruitment of estrogen receptor alpha (ERalpha). The aim of this study was to investigate the effects of PCB-126, a co-planar PCB prototypical AhR agonist, and of PCB-153, a non-coplanar PCB lacking dioxine-like activity, on Vtg expression in young fish (Spaurus aurata) after a 12 or 24h exposure to PCBs as well as 48h following PCBs removal. Vtg expression was evaluated by immunohistochemistry and by Western-blot analysis. Our results showed an increased Vtg expression following PCBs administration, with a maximum level after 12h of exposure to either PCB-126, PCB-153 or a mixture of both PCBs. Following this estrogenic activity, an anti-estrogenic activity was detected after 24h of incubation with PCB-126 (alone or mixed with PCB-153), suggested by a decrease in Vtg expression likely through AhR, as a consequence of a hypothetic defence mechanism to endogenous or exogenous ligands., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)