Assessment of oxidative stress of paracetamol to Daphnia magna via determination of Nrf1 and genes related to antioxidant system.

Paracetamol (APAP) is one of the most widely used anti-inflammatory and analgesic drugs in human being health care and has been universally detected in various aquatic environments. However, its potential adverse effects and toxic mechanisms on freshwater invertebrates still remain unclear. In the present study, the effects of APAP on the expressions of Nrf1 and the antioxidant related genes including GCLC, GST, GPX, CAT, TRX, TrxR and Prx1 in Daphnia magna (D. magna) were evaluated after 24, 48 and 96 h, and the changes of GPX, GST and CAT enzyme activities, as well as the GSH and MDA content under APAP exposure for 48 h were also determined. Results showed that paracetamol affected the expressions of Nrf1 and antioxidant related genes in D. magna, which were related to the exposure time and concentration of APAP. Nrf1 was inhibited at 48 h, but induced at 96 h under the APAP exposure, being about two fold of the control in 5.0 μg/L. CAT were significantly induced in all treatments. But Prx decreased in an concentration-dependent manner in all treatments. In comparison with the mRNA expression, antioxidant enzymes activity displayed less changes in D. magna. Overall, APAP exposure altered the expression of Nrf1 and genes related to antioxidant system and disturbed the redox homeostasis of D. magna.