Toxic Effects Of Simvastatin And Paracetamol On Daphnia Magna

Pharmaceuticals and personal care products(PPCPs)are a sort of emerging pollutants that have received increasing attention in recent years.Although the half-life periods of most PPCPs are relatively short,a “steady state of PPCPs” phenomenon is observed in the aquatic environment due to its large amount of use and frequently detection in the aquatic system in the low trace level.In spite of their lower concentration,humans and aquatic organisms may be in face of receiving the long-term exposure of PPCPs which posts a potential threat to human health and ecological system because of theirs strong biological activities,bioaccumulations and slow degradation characteristic.As widely used drugs,simivastatin(SV)and paracetamol(APAP)have been detected in various environments such as the urban wastewater and surface water.However,there are currently limited studies which reported the potential effects of simvastatin and paracetamol exposure on freshwater invertebrates.In this study,the model organism Daphnia magna was selected as a test organism,and the toxic effects of simvastatin and paracetamol on crustacean Daphnia magna were investigated at three different levels of mRNA transcriptional expression,enzyme activity response and individual physical change.When organism is exposed to environmental pollutants,the defense system and detoxification reactions of organism can initiate.The responses at the molecular level,which can reflect toxic effects of environmental xenobiotics,may initially be detected.In the present study,we established the quantitative PCR method for the target genes related to the antioxidant defense and detoxification systems(Nrf1,GCLC,GPxs,TRX,TrxR and Prx1).And then we also evaluated the effects of SV and APAP on the expression of the genes after 24 h,48 h and 96 h exposure by use of RT-PCR.The expressions of the target genes in D.magna showed that SV and APAP could disturb the normal functions of detoxification and antioxidant systems in different concentrations.Nrf1 showed inhibition at 24 h and 48 h and up-regulation at 96 h under both SV exposure and APAP exposure.At the enzymatic activity level,the response of the enzymatic activity of GST,GPX,SOD,CAT and change of GSH and MDA content under different concentrations of simvastatin and paracetamol exposures for 48 h showed the normal function of detoxification system and the antioxidant enzyme system of D.manga was disturbed.In particular,the contents of GSH and MDA showed a decreasing trend compared to the control.At the individual level,it reflects its toxic effects of APAP to D.manga in 21-day APAP chronic toxicity test.The lethal toxicity was observed in highest concentration group(5000 ?g/L),and all the subjects died at 18 days.The results of chronic toxicity test showed that with the increase of concentration,the molting frequency showed a parabolic response pattern which displayed promotion in lower concentration(5 and 50 ?g/L),while exerted inhibition in higher concentration(500 and 5000 ?g/L),and the intrinsic growth rate showed a decreasing trend with increasing concentration.In this study,we established the RT-PCR method of Nrf1,GCLC,GPxs,TRX,TrxR and Prx1 genes in D.magna and analyzed the toxic effects of simvastatin and paracetamol on the expression of the target genes related antioxidant defense and detoxification systems in D.magna.We also investigated the responses of antioxidant related enzymes of D.magna under SV and APAP exposure and the toxic effects of paracetamol on the growth and reproduction of D.magna at the individual level.This present investigation provided a scientific basis for the assessment of the ecological risk of the typical PPCPs(eg.simvastatin and paracetamol)to aquatic organisms,especially aquatic invertebrates.In addition,it has laid the foundation for further study of the toxic effects of simvastatin and paracetamol on crustaceans.