Investigação do efeito do herbicida glifosato sobre o estresse oxidativo e parâmetros metabólicos no peixe híbrido jundiara (Leiarius marmoratus x Pseudoplatystoma reticulatum)

Abstract

The use of herbicides in an indiscriminate and recurrent manner increases the chances that they will be deposited in the environment or even affect non-target organisms, especially when considering the water bodies that surround agricultural production areas. Glyphosate is one of the most widely used non-selective herbicides in the world due to its cost-effectiveness. Roundup Original® is the most used formulation in the production of transgenic soy, in which the State of Mato Grosso stands out internationally. Fishes are more sensitive to poisoning events than mammals. Information on herbicide-induced changes to these organisms is still limited, especially with respect to hybrid fish. The objective of this research was to perform an extensive analysis of several parameters of the jundiara fish (Leiarius marmoratus x Pseudoplatystoma reticulatum), a hybrid with important commercial appeal in the region. For this purpose, analyzes were carried out on oxidative stress, For this, oxidative stress analyzes were performed, such as dosage of thiobarbituric acid reactive species (TBARS), protein carbonylation, enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-tranferase (GST) as well as the non enzymatic antioxidants, ascorbic acid (ASA) and reduced glutathione (GSH), and the activity of acetylcholinesterase (AChE) in liver, brain, muscle or gill tissues. In addition, the plasma, liver tissue and peripheral blood of the animals were also submitted to analysis. The increase in the presence of TBARS in the liver and in the muscle tissue of the fish, as well as the increase of the protein carbonylation in the same tissues, as well as the reduction of the enzymatic antioxidant responses, SOD, CAT and GPx and the increase of GST corroborated the hypothesis That Roundup is capable of causing changes of this level even at low exposure dosages, such as 1.357 mg L -1 . Parameters such as decreased acetylcholinesterase (AChE) and the increase of transaminases in plasma (ALT and AST) or alterations of glycogen, glucose, lactate and protein levels in fish tissues have confirmed that an intoxication event was initiated causing a variety of negative organic responses. The analysis of hematological parameters (hemoglobin, hematocrit, red blood cells count and white blood cells count) also provided useful data to observe that the blood changes caused by the herbicide are also notable. In addition to the above, the increased frequency of micronuclei (MN) appearance indicates that animals exposed to Roundup may have suffered a genetic damage. Histological findings showed that there was no significant change in liver tissue completeness, which may have been motivated because the exposure did not exceed 96 hours and also because the dosage chosen was not able to cause this type of damage. In general, given the findings obtained through several analyzes, it is possible to propose that Roundup Original® is a substance with significant toxic potential to aquatic organisms, alerting to the need for awareness of its use and associated risks, as well as for the development of future studies that corroborate the data found and complement them with new information enriching the perception of the amplitude of its effects.