Determination of antioxidant system and xenobiotic metabolizing enzyme activities in rainbow trout (Oncorhynchus mykiss) treated with mifepristone

Mifepristone is a drug used in the treatment of optional medical abortion, Cushing's syndrome, and some types of tumors. It is widely used in some countries. For this reason, it is transported to aquatic environments via sewers. The effect of mifepristone on aquatic organisms is not known exactly. In this study, our aim was to determine the effect of mifepristone on CYP1A-associated 7-ethoxyresorufin O-deethylase (EROD), CYP3A-associated erythromycin N-demethylase (ERND), glutathione S-transferase (GST) and antioxidant enzyme activities, catalase (CAT) and glutathione reductase (GR) activities in rainbow trout (Oncorhynchus mykiss). For this purpose, 32 rainbow trout were divided into four groups as control, solvent control (DMSO), 100 ng/L treatment group, and 500 ng/L treatment group. Fish were treated with mifepristone at the indicated doses for 96 hours. Microsomes and cytosols were prepared from liver tissues. EROD and ERND activities were measured in microsomes. GST, CAT and GR activities were measured in cytosols. There was no difference between control and solvent control in enzyme activities and mifepristone used at two different doses. The results of this study showed that mifepristone has no acute effect on CYP1A, CYP3A, GST, catalase, and glutathione reductase enzyme activities. Mifepristone has no toxic effect on antioxidant system and xenobiotic metabolizing enzyme activities in fish at these doses and within this administration period.