Transcriptome analysis of the brain of the gilthead sea bream (Sparus aurata) after exposure to environmental concentrations of human pharmaceuticals

Abstract

Pharmaceuticals are being released into the environment in extremely large quantities on a regular basis. Ingested drugs are eventually excreted from individuals, as well as they are released from manufacturing and disposal of unused or expired drugs ultimately winding up in the effluent of wastewater treatment plants and aquatic environments. In order to assess the long term effects of exposure to environmentally relevant concentrations of representative pharmaceutical compounds we have exposed the gilthead seabream (Sparus aurata) to representative drugs found at ng-μg-L-1 levels in surface- ground and coastal waters. Acetaminophen (APAP), Carbamazepine (CBZ) and Atenolol (AT) were used as model compounds to assess the effects of low level, long term exposure on the expression of the brain transcriptome. The treatment with the greatest number of differentially expressed genes was CBZ with 467 features, compared with 226 for APAP and 4 for AT. The selected vehicle, DSMO, didn’t show any significant expression changes in comparison with the SW control. Out of all these features, only one was common between all the three treatments. This feature was identified by homology search as Sparus aurata cytochrome c oxidase subunit I mRNA. No other feature was common both between APAP and AT nor CBZ and AT. However, there were 130 common features between the APAP and CBZ treatment. Functional annotation clustering and enrichment analysis of APAP and CBZ candidate genes in DAVID revealed treatment specific activation of different pathways and processes, with energy-related features present in all the applied treatments.