(oncorhyncus mykiss) hepatocytes induced by bisphenol a

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The present study was carried out to examine caspase-3 activity in cytotoxicity of isolated rainbow trout (Oncorhyncus mykiss) hepatocytes induced by bisphenol ...

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Volume 25 – No. 4/2016, pages 1167-1174

Fresenius Environmental Bulletin

CASPASE-3 ACTIVATION IN CYTOTOXICITY OF ISOLATED RAINBOW TROUT (ONCORHYNCUS MYKISS) HEPATOCYTES INDUCED BY BISPHENOL A Burak Kaptaner1 and Ertuğrul Kankaya2 Department of Biology, Faculty of Science, Yuzuncu Yil University, 65080 Tuşba, Van, Turkey 2 Faculty of Fisheries, Yuzuncu Yil University, 65080 Tuşba, Van, Turkey

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including fish, are a major target of BPA and environmentally relevant concentrations of this substance have been reported to cause altered sex differentiation, gonadal abnormalities, and hepatic vitellogenin induction [2]. Apoptosis is an early indicator of acute and chronic chemical stress and serves as a warning regarding the loss of cellular function and structure [3]. Caspases are the primary drivers of apoptotic cell death and are regulated by a variety factor under physiological and pathological settings. Initiator caspases (caspase-2, -8, -9, and -10) cleavage the inactive precursor forms of effector caspases (caspase-3, -6, and -7) and activates them and caspase-3 in an effector caspase expressed in cells undergoing apoptosis and plays a central role in mediating nuclear apoptosis, including chromatin condensation, DNA fragmentation, and cell blebbing [4]. Fish cells used in toxicological studies are practical and advantageous tools allowing widely different species to be evaluated for their sensitivity to environmental contaminants at the cellular level [5]. Thus, they constitute an attractive model to understand time- and dose-dependent toxicant induction processes under defined experimental conditions [6]. Primary hepatocyte cultures from fish, such as rainbow trout, Oncorhyncus mykiss, are well characterized screening tools for the determination of the impacts of a single chemical or chemical mixtures [7]. Previous studies have mostly focused on the estrogenic effect of BPA on fish hepatocytes [8, 9, 10, 11]. However data on the responses of cytotoxicity in fish exposed to BPA is limited, especially in fish primary hepatocytes. In this study on rainbow trout, which frequently selected in toxicological studies for testing chemicals and recommended by the Organisation for Economic Co-operation and Development as a test animal [12], the hepatocytes were used to determine the dose- and time-dependent toxic effect of BPA on primary cultured hepatocytes of rainbow trout using lactate dehydrogenase release, and the role of caspase-3 in BPA-induced cytotoxicity.

ABSTRACT The present study was carried out to examine caspase-3 activity in cytotoxicity of isolated rainbow trout (Oncorhyncus mykiss) hepatocytes induced by bisphenol A. For this purpose, cultured hepatocytes were exposed to various concentrations of BPA (10, 50, 100, 250, 500, and 1000 µM) for 24 and 48 h. Cell viability was detected by measuring lactate dehydrogenase release into the medium. BPA demonstrated a cytotoxic effect on hepatocytes in a dose- and time-dependent manner, and was found to be severely toxic for hepatocytes with concentrations of 250 µM BPA and higher at both 24 and 48 h. Caspase-3 activity was significantly induced by BPA with 100 and 250 µM concentrations at 24 h, and 50 and 100 µM concentrations at 48 h. The results suggest that cytotoxicity of rainbow trout hepatocytes induced by BPA is mediated by caspase-3 activation. KEYWORDS:

Oncorhyncus mykiss, bisphenol A, cytotoxicity, caspase-3, isolated fish hepatocytes

INTRODUCTION Bisphenol A (BPA) is one of the important monomers used in the production of polycarbonates, epoxy resins, and other plastic products. It has received particular attention because of its large-scale production and widespread usage in the manufacturing of many consumer products, such as adhesives, baby bottles, dental sealants, compact discs, thermal papers, powder paints, cans, electronic parts, etc., encountered in daily life [1]. BPA has been reported to be estrogenic and possess endocrine-mediated adverse effects on wildlife and humans due to its weak binding to estrogen receptors. It is released into the environment through sewage treatment effluents, landfill leachate, or the natural degradation of polycarbonate plastics, and collects in rivers, lakes, and estuaries. Aquatic organisms, 1167

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