SELECTION OF BIOMARKERS TO EVIDENCE ATENOLOL EFFECTS ON FISH

VALDES, M. E.; AMÉ, M. V.; WUNDERLIN, D. A.; BISTONI, M. A.

Buenos Aires

Congreso; setac 2015; 2015

Atenolol is a β-blocker (β1 receptor antagonist) pharmaceutical used to treat hypertension and cardiovascular diseases. It has been frequently detected in several urban rivers given its high consumption, low hepatic metabolism (mainly excreted as parental drug), low percentage of removal in wastewater treatment plants (WWTP), stability upon microbial degradation and low sediment absorption. In the Suquía River basin (Córdoba, Argentina) atenolol has been detected in river water (up to 0,5 µg/L) and fish samples (up to 14 ng/g wet wt.). Given the few ecotoxicological data reported, different effect endpoints were measured under laboratory conditions on an already proposed bioindicator fish species inhabiting Suquia river, Jenynsia multidentata (Anablepidae, Cyprinodontiformes). The main goal of this study was to identify the most efficient biomarkers to evidence effects of atenolol on fish. Female adults of J. multidentata (0.5±0.2 g; 29±2 mm) were exposed to 0.002% methanol (control), 1 µg/L atenolol (environmentally relevant concentration) and 50 µg/L atenolol during 14 days (media renewed every 48 h). Effect biomarkers evaluated included: biotransformation (microsomal and cytosolic glutathione S-transferase-GSTm, GSTc) and oxidative stress (catalase-CAT, glutathione peroxidase-GPx and glutathione reductase-GR) enzymatic activity, acetylcholinesterase activity (AChE) and swimming behavior variables (distance and average speed). Discriminant analysis (DA) was carried out with Statistica 8.0 to select most efficient biomarkers to discriminate between exposed and control fish (3 groups). Standardized variables were included in the analysis by forward and backward stepwise methods. Upon 24 variables analyzed, AD by forward stepwise method selected 6 variables to discriminate between groups with 100% accuracy: brain AChE, intestine GSTm, intestine CAT, brain GR, gills GPx and gills CAT, of which the first 3 were the most important. Backward stepwise method only selected brain AChE as the minimal variable to discriminate between groups with 78% accuracy. Therefore brain AChE was the most effective biomarker to discriminate between atenolol exposed and control fish, under the laboratory conditions evaluated. This is why we propose brain AChE as a useful effect biomarker in fish exposed to atenolol under laboratory conditions.