Responses of branchial biomarkers of Prochilodus lineatus after prolonged exposure to sublethal concentrations of fipronil

SANTILLAN A; ONDARZA PAOLA MARIANA; MIGLIORANZA KARINA SILVIA BEATRIZ; DE LA TORRE FERNANDO

Congreso; 12th Biennial Meeting Society of Environmental Toxicology and Chemistry; 2017

Fipronil (Fp) is a broad-use pesticide, and exhibits severe toxicity and adverse effectsto non-target organisms, including fish. In this context, the presence of biochemicalresponses in fish is an effective tool for detecting sublethal effects from pesticideexposure. The responses of branchial biomarkers were evaluated on juveniles ofProchilodus lineatus after prolonged exposure to sublethal concentrations of Fp. Fish(n=32) were exposed to two nominal concentration of Fp (0.5 µg/L, C1 and 9 µg/L,C2) where toxicant was dissolved in methanol. Fish were kept in controlled conditionsin aquariums with daily renewal of the media. Control fish remained in unchlorinatedwater (Ctrl) and water with the maximum methanol concentration used (CtrlSv).Levels of Fp on water samples were also analyzed with liquid-liquid and GC-ECDextraction. After 21 days of exposure, fish were sacrificed and the branchial archeswere extracted. Enzymatic activity of superoxide dismutase (SOD), antioxidantcapacity against peroxyles (ACAP), content of reduced glutathion (GSH), levels oflipid peroxidation by TBARS as well as determination of oxidatively modifiedproteins (POx) were evaluated. Statistical differences between groups weredetermined using ANOVA (p< 0.05) followed by Tukey?s test. No mortality wasobserved in either experimental group and no significant differences between theparameters of Ctrl and CtrlSv were detected. Prolonged exposition to C2 promoted anincrease (20%) in enzymatic activity of SOD respect to Ctrl group. Also an increasein ACAP values (87%) was observed after exposure to C1, showing a decrease inantioxidant capacity. On the other hand, both concentrations promoted a decrease (5%)in GSH activity respect to Ctrl. In terms of oxidative damage, exposition to Fpconcentrations promoted an increase in TBARS levels (207%, C1 and 134%, C2);meanwhile, only C2 group showed a significant increase (41%) in POx levels. Theseresults suggest that exposure to Fp promoted an antioxidant response, which was notenough to prevent oxidative damage at the protein level and lipid peroxidation. Also,both concentrations proved to be an inducer of oxidative stress even at ambientrelevant concentrations.