Análise do Efeito da Contaminação do Glifosato no Camarão de Água Doce Macrobrachium rosenbergii: Efeito Letal, Neurotóxico e sobre o Sistema Antioxidante

Abstract

Brazil is an agricultural country, making use of several chemical inputs, among which stands out Glyphosate, highly used in soybean and corn crops, but with potential risk of contamination of soil and water in rural areas. The increase of the continental cultivation of Freshwater Prawn Macrobrachium rosenbergii in regions close to large rural areas leads to questioning about the effect of glyphosate contamination in these animals. The objective of this work was to analyze the effect of glyphosate on the mortality and physiology of freshwater prawn M. rosenbergii by means of the LC50 assay for 96 hours at concentrations of 0, 10, 50, 100 and 150 mg / L glyphosate and short-term test with 100 mg / L glyphosate contamination at 2, 6, 9 and 24 hour exposure periods. Em ambos os ensaios foi realizada coleta de hepatopâncreas e músculo para análises de marcadores bioquímicos de neurotóxicidade (colinesterase) e do sistema antioxidante (LPO e enzimas catalase, GST e GR). Os animais submetidos a 150 mg/L de glifosato apresentaram 100 % de mortalidade. The other concentrations had partial mortality rates. The LC50 was determined using the Probit statistical tool, determining the concentrations of 125.63 mg / L in 48 hours, 68.38 mg / L in 72 hours and 52.52 mg / L in 96 hours. In animals surviving the LC50 assay, no variation in cholinesterase activity, LPO, catalase and muscle GR and hepatopancreas of the survivors was observed, but there was a reduction in GST enzyme activity in muscle from animals submitted to 10 mg / L glyphosate and also agitation was observed, followed by paralysis in the animals from 2 to 10 hours after contamination. Animals undergoing short-term exposure to glyphosate showed paralysis at 2, 6 and 9 hours after contamination, returning to similar movement pattern at 24 hours, which was similar to behavioral changes perceived in LC50. The GST activity in hepatopancreas after 2, 9 and 24 hours of contamination was increased. The animals also had cholinesterase inhibition in hepatopancreas in 2 (58.27%), 6 (81.96%) and 9 hours (22.9%) after contamination, with maximum inhibition found at 6 hours and absence of inhibition observed after 24 hours. In relation to the catalase enzyme of hepatopancreas, there was elevation of the activity in 2 hours of contamination. No changes in LPO and muscle GR and hepatopancreas activity were observed throughout the trial. The LC50 values found indicate that glyphosate is toxic to M. rosenbergii. Inhibition of cholinesterase, together with altered motility and increased GST activity when the animals were exposed to a short period of contamination, indicate that inhibition of cholinesterase induces the biotransformation reaction of glyphosate via GST, This is the neurotoxic effect of glyphosate, with a return to cholinesterase activity and swimming behavior at the levels observed in the control animals in the short term after contamination.