Parâmetros toxicológicos em piavas (Leporinus obtusidens) e jundiás (Rhamdia quelen) após exposição a uma formulação comercial de glyphosate

Abstract

The commercial formulations of glyphosate herbicide have been widely used in agriculture and pisciculture for controlling plant weeds. Fish can be affected when drainage water reaches water courses, causing a disturbance in the aquatic ecosystem. Therefore, the aim of this study was to investigate whether exposure to a commercial formulation of glyphosate affects toxicological parameters in piavas (Leporinus obtusidens) and jundiás (Rhamdia quelen). Piavas were exposed to: 0 (control), 3, 6, 10 or 20 mg/L of glyphosate (480 g/L) and jundiás to 0 (control), 0.2 or 0.4 mg/L, both for 96 h. Enzymatic (AChE), hematological (hematocrit, hemoglobin and erythrocyte and leucocyte count) and metabolic (glucose, glycogen, lactate, protein and ammonia) parameters were analyzed in different tissues of these species. In addition, oxidative stress parameters, such as activity of the antioxidant enzyme catalase, protein carbonilation and TBARS levels were analyzed. The results showed that brain acetylcholinesterase (AChE) activity decreased significantly in both species exposed, but there was no significant change in the muscle tissue. There was a decrease in hematological parameters in blood of piavas. After exposure to this herbicide, both species demonstrated metabolic disorders. In piavas, there was a reduction of glycogen and an increase of glucose in hepatic tissue, and a reduction of muscle glycogen and glucose. Lactate and protein showed a decrease in hepatic tissue after exposure to all concentrations of the herbicide, but in muscle tissue there was an increase in these metabolites. The levels of ammonia increased in both tissues after exposure, varying with the glyphosate concentration. In jundiás, there was an increase of hepatic glycogen, but a reduction of muscle glycogen at both concentrations tested. Glucose showed a decrease in liver and increase in muscle. After exposure to this herbicide, the levels of lactate were increased in both tissues. The levels of protein were increased in hepatic tissue and decreased in muscle tissue, while the levels of ammonia showed an increase at both herbicide concentrations in both tissues tested. Catalase activity showed an increase in jundiás, but not in piavas. TBARS levels showed an elevation in muscle tissue in jundiás while in piavas there was an increase in hepatic tissue. An increase in protein carbonyl formation in liver of jundiás was observed. In addition, there was an increase in mucus parameters in piavas. These results indicate that the parameters measured may be good indicators of herbicide contamination in piavas and jundiás of the southern region of Brazil.