Effect of malachite green in rainbow trout (Oncorhynchus mykiss) on xenobiotic metabolizing enzyme activities and antioxidant system

Malachite green is a cheap organic dye used in many different industrial fields. It is mutagenic and carcinogenic chemical. Aquatic organisms are under the risk of malahite green exposure due to its usage in different fields. In this study our aim was to determine the effect of two different concentrations of malachite green on cytochrome P450 system and antioxidant system in rainbow trout (Oncorhynchus mykiss). For this purpose, 24 fish were randomly divided into three groups namely control, 0.1 mg/L malahite green administration group and 0.5 mg/L malahite green administration group. After 24 hours, 5 of the fish samples treated with 0.5 mg/L malahite green were died and remaining 3 samples were killed and liver samples were taken. The fish samples treated with 0.1 mg/L malahite green continued to be treated with malahite green for 54 hours. At the end of this time period, fish samples were killed by cervical dislocation and liver were taken and stored at -80° until used. 7-ethoxyresorufin-O-deethylase (EROD), erythromycin N-demethylase (ERND) and 7-pentoxyresorufin O-depentylase (PROD) activities of fish were determined in microsomes. Glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT) and glutathione peroxidase (GPx) activities were measured in cytosols. Highly elevated EROD activities were measured in fishes treated with 0.5 mg/L malahite green. PROD activities were increased with increasing doses of malachite green. ERND activities were higher in 0.1mg/L and 0.5 mg/L malahite green administration groups than that of the control group. However, these differences were not statistically significant. GST activities were not affected from the malachite green treatment. CAT activities of 0.1 mg/L malachite green administration group were higher than that of the control group. Similar to the catalase activity, GR activities of 0.1 mg/L malachite green administration group were higher than that of the control group. GPx activities of 0.1 mg/L malachite green administration group were less than that of the control group. However, this difference was not statistically significant. The role of CYP1A on the metabolism of malachite green was also determined with in vitro studies. CYP1A associated EROD activity inhibited with increasing concentration of malachite green. All of these results clearly indicate that malachite green has modulatory effect on EROD, PROD, CAT and GR activities in rainbow trout.