| Atrazine (ATZ) is the most common pesticide of freshwater ecosystems in the world. In the recent years, more and more studies suggested that ATZ could induce the oxidative damage and endocrine disruption effects in different organisms, however, the mechanism especially in the aquatic organisms had only received limited attention. Thus, to better understand the oxidative stress process and endocrine disruption induced by ATZ, the present study examines concentration-dependent oxidative stress and endocrine disruption in the adult zebrafish liver and gonad by determining the malondialdehyde (MDA) and GSH contents and the activities of SOD and CAT, the gene expression related to oxidant and endocrine systems in zebrafish. Furthermore, the proteins expression patterns in the liver induced by ATZ were also analyzed by proteomics method.The effects of ATZ exposure on the induction of oxidative stress and the alteration of the related gene expression were studied in liver and gonad samples from zebrafish. Antioxidant enzyme activities (SOD and CAT), in addition to the GSH and MDA content, in the liver altered significantly, the mRNA levels for the genes encoding these antioxidant proteins, such as Cu/Zn-sod, Mn/Zn-sod, cat, and gpx, were up-regulated significantly in the liver when zebrafish were exposed to various concentrations of ATZ for 14 days. However, the mRNA induction patterns were not in accordance with those of antioxidant enzyme changes in the liver and gonad. Moreover, the transcriptional expression of mitochondrial inner membrane genes related to ROS production, such as ucp-2, bcl-2, coxI and ndi were altered significantly in high ATZ treatment groups. However, the ATZ treatment did not induce any apparent changes in the transcriptional expression of ATPo6, which are related to the ATP synthesis.Secondly, we found that ATZ exposure could induce the alteration of GSI (gonad/body weight×100) and the genes related to the endocrine system in both male and female zebrafish after 14 days exposure. For example, low concentrations (1μg/L) could increase GSI, but reduce at higher concentration. Furthermore, the mRNA leveal of vtg1 and vtg2 were up-regulated significantly in the liver of female zebrafish, and also the mRNA levels of cyp19a and cyp19b were up-regulated in the ovary and brain, respectively. However, in the male zebrafish, the mRNA levels of vtg1 and vtg2 were not induced significantly in the liver of male zebrafish. The mRNA leveal of cyp19a was up-regulated significantly in gonad.In addition, cell borders became obscure and hepatocellular vacuolar degeneration was observed by hepatic histopathological analysis. Moreover, two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MALDI-TOF-TOF MS), was used to screen hepatic responses in adult female zebrafish. Seven proteins were found to be up-regulated more than 2-fold, whereas six protein spots were down-regulated more than 2-fold after 10 and 1000μg/L ATZ treatment for 14 days. These differentially expressed proteins accounted for a variety of cellular biological processes, such as response to oxidative stress, apoptosis, oncogene etc..In summary, in the present experiment, we found that ATZ exposure can induce significant changes in antioxidant enzymes activities (SOD and CAT), and GSH and MDA contents, mRNA levels of genes related to encode antioxidant proteins and endocrine system and the hepatic protein profiles of zebrafish following ATZ exposure. The information presented in this study will be helpful in fully understanding the mechanism of oxidative stress and endocrine disruption effects induced by ATZ in fish. |
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