Efeitos da exposição ao glifosato sobre biomarcadores de estresse oxidativo em jundiás (Rhamdia quelen)

Abstract

In this study, we use as model a native fish species from Rio Grande do Sul, the Rhandia quelen (catfish). These specie stands out as one of the most promising because it has a rapid growth, high rate of fertilization and easy to adapt to non-native environments. Glyphosate is a systemic herbicide used to inhibit the growth of weeds. Its use, near to water reservoirs, makes it glyphosate flow into rivers and lakes, contaminating local species. This study aimed to evaluate the effects of exposure to glyphosate on biomarkers of oxidative stress in catfish. For this, catfish fingerlings weighing an average of 12 g were exposed to glyphosate herbicide at a dose of 11.29 mg/L for 30 days. To determine the dose of the herbicide, the LD50 value was previously determined in Artemia salina. At the end of treatment, animals were sacrificed and had tissues (brain, muscle, liver, kidney and blood) removed for analysis. Biometric evaluation was performed every two weeks and the glucose and triglyceride levels were measured at the end of treatment. Moreover, we evaluate the levels of thiobarbituric acid reactive species (TBARS), sulfhydryl groups (SH), and activity of the δ-aminolevulinate dehydratase enzyme (δ-ALA-D) and acetylcholinesterase (AChE) enzyme. There were no differences in length of the animals throughout the 30 days of treatment. However, there was a reduction of weight. Regarding glucose and triglyceride levels, no significant differences were observed. Our results show that treatment with sublethal dose of glyphosate causes oxidative stress in different degrees. Increases in TBARS levels were observed in the liver and brain. SH levels were increased in the liver, kidney and brain, and decreased muscle. The activity of δ-ALA-D was increased in the liver, muscle and brain. There was no significant difference in the AChE activity. Based on the results, we can conclude that the glyphosate herbicide in sublethal dose causes oxidative stress, but does not determine significant metabolic changes in the catfish.