A influência do herbicida FACET® (Quinclorac) nos níveis de corticosterona, metabólitos plasmáticos e nas defesas antioxidantes do fígado de girinos de rã touro (Lithobates catesbeianus Shaw, 1802)

• Ano de defesa: 2015
• Autor(a) principal: Coltro, Mariana de Lima
• Orientador(a): Oliveira, Guendalina Turcato
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ZOOLOGIA; HERBICIDAS; ANFÍBIOS; GIRINO; ESTRESSE OXIDATIVO; METABOLISMO
• Link de acesso: http://hdl.handle.net/10923/7738

Since the principles of management in agriculture by man, technology has increased exponentially, allowing rapid development of this sector. However, many improvements are linked to use of chemically synthesized compounds, with the environment and the human being exposed to these pollutants, often harmful. Nevertheless, the amount of these herbicides is increasing. The herbicide based on quinclorac, as Facet® acts as a growth inhibitor, immediately absorbed by germinated seeds, roots and leaves and then transported to the plant. This agent is commonly applied in rice fields and in southern Brazil, the quinclorac is most often detected in studies with agrochemical residues used on these crops and is considered a major water contaminant. Several animal studies have demonstrated the negative biological effect of this xenobiotic, as changes in behavior, development and production of corticosteroids, which may cause malformations, cell differentiation and reproduction problems. Given the high sensitivity of tadpoles to environmental stressors, we choose as model Lithobates catesbeianus species, which has, among ranídae family, a great plasticity and toughness, due probably to be an introduced species in Brazil. To perform this study were acquired 79 tadpoles with 4 months old, on stage 25 (pro metamorphic) of the Gosner table. Animals were divided into tanks of 60L of water with constant aeration in natural photoperiod and temperature, pH of 7. 4, fed ad libitum on chow. Since there was manipulation and euthanasia of animals, the study was submitted to the Ethics Committee on Animal Use (CEUA) of PUCRS. The herbicide was added at day 8 in X1 concentrations (0,05μg/L), X2 (0,1μg/L), X3 (0,2μg/L) and X4 (0,4μg/L). The objective of the research was to analyze the possible alterations in the activity of antioxidant enzymes and levels of lipid peroxidation (LPO) liver; as well as the levels of corticosterone (CORT), glucose and uric acid (UA) in plasma after exposure of the herbicide. Since there was no difference between groups control 7 days (C7) and control 14 days (14), except for the UA as the groups were compared with the C14, where they show the same development time of exposed. The results showed significant differences in LPO, especially in animals exposed concentration 0. 1 μ g/L (X1) of the herbicide; also induces the increased activity of GST, SOD and CAT; After it followed by a decrease in this activity where noticed in the case of SOD, CAT and GST, an inverse relationship between the concentration of the pesticide and the response of the enzyme system. However, these results did not determine an increase in lipoperoxidation and even cause death to the animal suggesting a high constitutive activity of these enzymes and / or the presence of a non-enzymatic antioxidant system rather desenvolvido. The plasma corticosterone levels showed differences between the groups X1 (0,05μg/L) and X4 (0,4μg/L), a decrease in X4, deducting a decreased responsiveness of animals to prolonged exposure front seven days, at higher concentrations of the pesticide; this response being coupled to increased glucose levels in X3. The UA levels showed a significant reduction in X4 group, however, for further findings on the use of this molecule and its role as an antioxidant by the non-enzymatic system will require new studies.