Alterations in Differentially Expressed Genes After Repeated Exposure to Perfluorooctanoate and Perfluorooctanesulfonate in Liver of Oryzias latipes

Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are considered biologically toxic due to their persistence in the environment. The effects of repeated exposure to these compounds on differentially expressed genes (DEGs) were investigated in liver of the medaka, Oryzias latipes. In this study, seven genes—except for cytochrome P450 3A (CYP450 3A)—were identified as DEGs that were downregulated in response to 15- and 30 days exposures to PFOA and/or PFOS. Four DEGs (c-type lysozyme, EF-1β, complement component C3-1, and NADH dehydrogenase subunit 1) returned to basal levels after 15 days of recovery after 30 days of exposure to the compounds. In contrast, three DEGs (transferrin, alcohol dehydrogenase class VI, and CYP450 3A) were still upregulated by PFOS after 15 days of recovery. In addition, the effect of PFOS showed more accumulation after 15 days of recovery than PFOA. These data suggest that PFOS accumulates more in tissue than PFOA and causes high cellular toxicity by way of suppression of the genes encoding transferrin and alcohol dehydrogenase class VI, whereas there is upregulation of cytochrome P450 3A.