Pharmaceuticals and personal care products are a growing concern in the aquatic environment. Compounds from the class of non-steroidal anti-inflammatory drugs are commonly detected in surface waters and have the potential to negatively affect aquatic organisms. The purpose of this experiment was to determine the acute and chronic effects of ibuprofen on rainbow trout (Oncorhynchus mykiss). Cyclooxygenase (COX) activity, vitellogenin (VTG) concentration and ethoxyresorufin-O-deethylase (EROD) activity were evaluated following waterborne ibuprofen exposure of trout to 1 and 10 mg/L in the acute exposure and 1, 32 and 1000 μg/L in the chronic exposure, along with an experimental control, E2 control of 1000 μg/L and an E2-ibuprofen mixed treatment. Ibuprofen did not inhibit COX enzyme activity in either gill or kidney tissue. To evaluate the estrogenic effects of ibuprofen, VTG concentrations were measured; by the end of the 56 day chronic exposure VTG concentrations significantly increased in all of the ibuprofen treatments relative to the controls. EROD activity may have been inhibited by ibuprofen but definitive conclusions could not be made. These findings indicate that more research needs to be done studying ibuprofen in aquatic systems. / UOIT

Cathepsins have been proposed as biomarkers of chemical exposure in the zebrafish embryo model but it is unclear whether they can also be used to detect sublethal stress. The present study evaluates three cathepsin types as candidate biomarkers in zebrafish embryos. In addition to other functions, cathepsins are also involved in yolk lysosomal processes for the internal nutrition of embryos of oviparous animals until external feeding starts. The baseline enzyme activity of cathepsin types H, C and L during the embryonic development of zebrafish in the first 96 h post fertilisation was studied. Secondly, the effect of leupeptin, a known cathepsin inhibitor, and four embryotoxic xenobiotic compounds with different modes of action (phenanthrene—baseline toxicity; rotenone—an inhibitor of electron transport chain in mitochondria; DNOC (Dinitro-ortho-cresol)—an inhibitor of ATP synthesis; and tebuconazole—a sterol biosynthesis inhibitor) on in vivo cathepsin H, C and L total activities have been tested. The positive control leupeptin showed effects on cathepsin L at a 20-fold lower concentration compared to the respective LC50 (0.4 mM) of the zebrafish embryo assay (FET). The observed effects on the enzyme activity of the four other xenobiotics were not or just slightly more sensitive (factor of 1.5 to 3), but the differences did not reach statistical significance. Results of this study indicate that the analysed cathepsins are not susceptible to toxins other than the known peptide-like inhibitors. However, specific cathepsin inhibitors might be identified using the zebrafish embryo.