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The presence of the transmembrane proteins of the ATP-binding cassette (ABC) family, which perform the efflux of several substances, contributes to the survival of aquatic organisms in a contaminated environmental. Those proteins provide a phenotype named the multixenobiotic resistance mechanism (MXR) by performing the efflux of a wide range of endogenous and exogenous compounds (ABCB) and biotransformation products and anionic compounds (ABCC). The aim of the present study was to evaluate the cellular defense pathway of an established culture from zebrafish hepatocytes (ZF-L) after 24 and 48 h of exposure to glyphosate and Original Roundup®, an herbicide used globally. Through abcb4, abcc1, abcc2 and abcc4 gene expression, ABCB and ABCC2 protein expression and ABC pump activity in ZF-L cells exposed to glyphosate and Roundup®. The results showed an increase in ABCB gene and protein expression; however, although ABCC2 showed an increase in gene expression, its protein expression was lower than in the control group. Regarding ABC activity, only exposure to Roundup® at the lowest concentration showed an increase at 48 h, but in the presence of inhibitors, both glyphosate and Roundup® appeared to modulate ABC activity, reducing its inhibition and returning activity to levels without inhibitor.

Agroquímicos são amplamente utilizados na atividade agrícola com o objetivo de aumentar a produção e melhorar a qualidade dos alimentos, no entanto podem vir a gerar danos ao meio ambiente e a organismos não-alvo. Dentre esses pesticidas encontra-se o herbicida glifosato, o qual vem sendo mais utilizado mundialmente. Seu mecanismo de ação se dá através da inibição da enzima 5-enolpiruvilshikimato-3- fosfatosintase, intermediária da síntese de aminoácidos aromáticos essenciais em plantas. Pouco se sabe sobre os efeitos da substância glifosato em animais, pois os estudos realizados visam principalmente os efeitos da formulação comercial, a qual contém surfactantes e outras substâncias inertes. Tendo isso em vista, esse estudo avaliou o efeito do glifosato no teleósteo Danio rerio considerando parâmetros de estresse oxidativo, atividade e expressão da acetilcolinesterase e parâmetros reprodutivos. Foram feitas exposições a 5 mg/L e 10 mg/L de glifosato, mais um grupo controle por 24 e 96 horas, somente com peixes machos. Para análise bioquímica foram retirados cérebro, brânquias e músculo; para análise molecular, cérebro e músculo; e para análise na qualidade espermática dos peixes, os testículos. Quanto às análises bioquímicas houve um aumento na capacidade antioxidante contra radicais peroxil nas brânquias na concentração de 5 mg/L após 24 horas de exposição; uma redução na peroxidação lipídica no cérebro na maior concentração (10 mg/L) após 24h e um aumento da mesma em músculo, também em 10 mg/L, após 96 horas. Não foi observada alteração na geração de espécies reativas de oxigênio decorrente da exposição ao glifosato, assim como na atividade da enzima acetilcolinesterase; já na expressão gênica desta enzima houve uma diminuição no cérebro após 24 horas de exposição e um aumento no cérebro e no músculo após 96 horas. Quanto à qualidade espermática dos peixes, houve uma redução na motilidade e período de motilidade dos espermatozóides nas concentrações de 5 mg/L e 10 mg/L em ambos tempos de exposição; na concentração de 10 mg/L ainda houve uma redução da funcionalidade mitocondrial, integridade de membrana do espermatozóide e integridade de DNA após 24 e 96 horas. Sendo assim, o glifosato se mostrou capaz de alterar o balanço oxidativo dos tecidos do peixe Danio rerio bem como alterar significativamente a expressão gênica da enzima acetilcolinesterase. Além disso, nossos resultados demonstram que o glifosato pode interferir na reprodução deste animal, através da redução de sua qualidade espermática. Glyphosate-based herbicides are toxic to animals and its action mechanism is not well understood. In the present study, generation of reactive oxygen species (ROS), antioxidant capacity against peroxyl radicals and lipid peroxidation were evaluated in males of Danio rerio exposed to 5 and 10 mg/L of glyphosate for 24 and 96 hours, well as the activity and expression of acetylcholinesterase enzyme. It was observed an increase on the antioxidant capacity in gills after 24 hours in animals exposed to 5 mg/L of glyphosate. There was a decrease in lipid peroxidation in the brain at the higher concentration (10 mg/L) after 24 hours and an increase in muscle after 96 hours in animals exposed to the higher concentration. No alterations were observed in the generation of reactive oxygen species caused by glyphosate exposure. Acetylcholinesterase (AChE) activity was not altered in muscle and brain of animals exposed to both glyphosate concentrations after 24 and 96 hours. However, gene expression of this enzyme was reduced in the brain after 24 hours and enhanced in both, brain and muscle, after 96 hours. Thus, contrary to previous findings that attribute the imbalance in the oxidative state in animals exposed to glyphosate-based herbicides to surfactants and other inert compounds, the present study has demonstrated that glyphosate per se is able to trigger this same effect. Also, although glyphosate concentration employed was not able to alter AChE activity, it was demonstrated for the first time that this molecule affects ache expression in zebrafish Danio rerio. Glyphosate is a systemic, non-selective, herbicide widely used in agriculture worldwide. It acts as an inhibitor of the enzyme 5-enolpyruvoylshikimate-3-phosphate synthase by interrupting the synthesis of essential aromatic amino acids. This pathway is not present in animals, although some studies have shown that the herbicide glyphosate can affect fish reproduction. In this study the effect of glyphosate was investigated on sperm quality of the fish Danio rerio after 24 and 96 hours of exposure, at concentrations 5mg/L and 10 mg/L, over the control group. The concentration of spermatic cells, sperm motility, motility period were measured employing conventional microscopy and the mitochondrial functionality, membrane integrity and DNA integrity were measured by fluorescence microscopy using specific probes. No significant differences in sperm concentration were observed. However, the sperm motility and motility period were reduced in both glyphosate concentrations and both exposure periods. The mitochondrial functionality, membrane and DNA integrity were reduced at the highest concentration in both experimental times. The results showed that glyphosate can induce harmful effects on reproductive parameters in Danio rerio and, this change would reduce the fertility rate of these animals.